Username change logs can be a privacy invasion, as pointed out below.
If instead you want to track and ban changes, you can think of 'ban suspension'.
"Ban suspension" means that if a suspended user changes their username to avoid punishment, Twitch will automatically ban that user from the channel.
Through this, it is possible to operate a warning system beyond the rigid punishment system of bans.

It may be awkward because it is a sentence through translation, so I ask for your understanding.

What you ask for is a potential violation of user privacy and safety.
AVexedFrog mentioning being stalked is an excellent reason to NOT permit what you request.

I'm really not seeing a legitimate purpose for this information that couldn't already be handled by some other means.

Either a user is doing something banworthy, in which case you should respond with a ban and ban reason, or they're not doing anything that would justify your intrusiveness.

I actually got stalked several times throughout my streaming career. Seeing username history would have helped ALOT. I’ve seen the comments about trans people, I think if it’s a name or even just to have some privacy in total the username should be half censored. So it could be like Username123 but censored like *****ame123 that way there is still a sense of anonymity.

I initially thought this was a good idea and had upvoted it but removed my vote after thinking about it more as I think it would be more harmful than good. This would be harmful to people who previously had personally-identifying usernames whom now wish to remain more anonymous, e.g. to avoid stalkers or other risks associated with using their government name on social media, or to avoid outing themselves as trans (in the case that their dead name or gendered words were in their previous username).

As a workaround, to learn more historical information about current chatters for moderation purposes, broadcasters and mods can type /user <username> in the chat to get a history of a user's chat messages, including moderator comments. Full history regardless of username changes is available for the username provided, assuming you know the *current* username. There is a limitation that this command won't work for old usernames, e.g. if someone behaves poorly in chat and no moderation actions were taken at the time of the incident, if you try to do anything after they've changed their username (e.g. days/months later), you risk not being able to look them up if they've changed their username. This requires moderators and broadcasters to act within a reasonable amount of time of the event, usually immediately, which is not an unreasonable expectation given that's what they do now to keep chats safe (banning, timing out, deleting messages as needed while live).

And maybe this is a hot take, but any third-party system that relies on a mutable property as a primary identifier (like usernames) and does not uniquely identify users with their Twitch user ID, a publicly-available attribute, is a poorly-designed system. Usernames, display names, and user ID's are all available with every incoming chat message via Twitch's IRC chat system, as well as via the Helix API endpoints (e.g. Get Users → https://dev.twitch.tv/docs/api/reference#get-users), so these third-party tools are given the resources to do this correctly—if they don't, that's on them, and if you are limited by these tools, I suggest finding other tools. I don't think Twitch should be outing historical usernames as a workaround for these poorly-designed third-party tools.

The fact that you can still track a user based on their id via the `users?login=<username>` endpoint means this feature is redundant if that information is kept in a moderation log. Though at the moment that requires external log(s) as this information isn't provided natively on the website. This also would eliminate the need for previous user names to be viewable to moderators. Currently, the only way to track user name changes is either moderator comments or off-platform logs. That being said, I can see why certain sensitive issues might arise that not everyone wants to be tracked. (i.e. a name change for a transgender person in regards to their Twitch username)

Not likely going to happen. In the past ComanderRoot and more had a tool that let you see Name history but was given a C&D and from what i seen twitch wants to respect users privacy. The feature would be more harmful than helpful.

Most of the issues stated here can be solved with the tools given and effort

Bots like StreamElements dont even log a users name change either when they probably could but rather reespect peoples privacy. If you're a moderator than i recommend using proper ban reasons, the mod note tool and just reading the users chat history .

Good idea, temporarily banning someone and then they change their name after their ban will lead to another temporary ban instead of a permanent ban.

Correct as noted before I have had a chatter first thing talking in the chat act like “look at me” mindset, I reached out to a recent raider that they guided to my channel I mod in and asked that raider about said old name and if they look up the old name it will not come up with anything any more as that old name doesn’t exist any more, I only was informed by the mod of the other channel that they changed their name very very recently.

Another example is that a channel I mod in the other mod changes her name ever two months mostly the same thing they still retain their mod status but it can be a little alarming to the streamer and other mods.

A new account is a new account and is completely different, a dead name account sure has its privacy concerns however I am not going to go looking at a chatter unless they are a concern and new to the channel I mod in. At the very lease the last 6 months while that old name is in the “not available stage” to be noted and linked to that chatter.

Long story short the options for the previous names allows the stream to not get an unwelcome surprise / the mods to not have to always remember and has an option to note and not manually note things them self I would rather twitch note it then my self note problem children in the mod comments (that can’t be deleted and are ever lasting)

Even if like a foreign name shows the English and language of the user in the list. It could show in chat of the user for the mods to see namehere (old name here): message in chat

Renaming the user doesn't unban the user, but certainly causes confusion with the moderation team if he asks for a unban and the reason was the trolling nickname which some of the channels I mod for is against their rules.

Because ALWAYS instead of being honest saying "sorry I used a nickname XYZ which was against the chat rules but now I changed my nick", they just say "I did nothing to be banned".

PS. Yeah, our moderation team uses the mod comments on card to mark the ofensive/trolling nickname now. But some legacy changed nick users from before unban was a thing so once in a while still shows up.

The whole naming system of Twitch is bad. Why not everybody has an ID? And if you ban TwitchUser123 then after it is renamed to GameWatcher456 it is still banned in your channel.

Thinking on what Elle and Hoops said. I think the better would be twitch giving a 3 months timespam to see the previous username of an given account which had been changed the nickname previously, and on the first time someone say something on chat. Like the first user message alert they implemented a while ago. It could something like that. "Say hi again to TwitchFan123, formely KappaFan2014"

The whole point of seeing a previous username is for an example like the below

so that if mods are having a difficult time with “TwitchUser123” and follow standard mod rules (Chat Warn, 3 Timeouts then ban) but all of a sudden that username is no longer turning up to chat and there is now “GameWatcher456” in chat who is actually “TwitchUser123” with a username change we can see that, and they’re being equally as annoying, we can see that it is that user

This is why a username log is handy for mods. Especially when you’re dealing with 500+ Chat users you can’t remember every timeout, and don’t put username in your mod notes because of it.
Happy for it to be behind a verification wall so twitch can say “this person accessed your username history”
Also happy For it to be their previous username not all 40 of them.

On Elle's point below, I do agree that there could be issues with revealing old usernames. Alternatively, if chat logs were to be linked to the user instead, then we'd be able to see chat logs from someone prior to their account name change. Maybe the addition of "last name change" would protect the safety of those that have changed their username with personal/good intentions, as opposed to those ban evading.

Example: If I had messages in a chat then changed my Twitch name, my logs would then show as blank. If I said something inappropriate and was banned but then changed my name, my logs would disappear and I could then easily request an unban whereby moderators would be unable to see my chat history.

If we could see the full history of a user's logs, regardless of username history, mods can then understand why users with "blank logs" that are ban evading were banned. Completely agree that for people's personal safety, revealing previous usernames would be a risk to many. Thanks for bringing that point up ElleRows.

As a transgender streamer- who has had an account since 2013 --- and 2015 respectively, my former name was part of my username. so having mods see my past username would risk outing me and dead naming me as a trans person.

but I would propose a feature that says *username last changed x days ago* or *recently changed username* without revealing the past username

i mean there was a reason twitch sent commander root a letter saying he had to stop tracking accounts past usernames 2 years ago

oh yes please

Yes, please!

I agree this needs to be implemented. This will help a lot with unban requests and knowing the history of the username.

Addition of previous usernames in logs would prevent the unbans of users with "blank" chatlogs that were previously banned, will avoid ban evasion. Since removal of third party sites showing this data, there's been no way to find previous usernames in Twitch which causes some issues with moderating.