Twitch is not GDPR compliant by not providing this information.
As someone who regularly gets banned for people thinking that I am a bot, in channels I do not know about, because someone has put my username on a list of names they "suggest" to be banned (and I was able to successfully request to be removed from the "popular" ones), and as a victim of harassment by both a streamer who has since received a permanent channel suspension and some of their viewers who have spread rumors and lies of purported abuse, even though I barely, if ever, interacted with them, in an attempt to get me banned from various channels.

Also, if I am not mistaken, I do believe I had originally submitted this. I am not sure why it shows as "Anonymous" now and isn't visible from my profile. 🤔

Aegis_of_Avalon is completely wrong and clearly very unintelligent. Anybody with even a single brain cell in their head would be able to see why this would be useful. Sure most of the time people are banned for being stupid, but banning is done by actual people, so there does not necessarily have to be a reason for the ban. There are also ways the creator themselves could be at fault for the ban especially given how sensitive society has become. I have never been banned from any channels (that I know of), but I believe it would be a nice feature.

No, there isn't a reason for the person in question to be able to see where they are currently banned from. Outside of one's own stream, private/public lobby, they should carry themselves with a specific deminer at all times. Thus, a ban appeal is never warranted, or should ever be allowed. Fool me once, shame on you, fool me twice...

It might be a good idea to also provide the reasons those channels ban the users from chat

I think a way of doing this is making a request section to Twitch. Where you can request Twitch to send you any channels you are banned from, but they over look it to make sure the ban wasn't Recent or you're not constantly getting banned or reported.
I had a situation years ago where I was speaking with a streamer and we were talking about S*x work and how it's okay. Apparently their mod didn't like the convo and banned me then told the streamer "We'll talk about it later" when the streamer asked their mod why they banned me.

I was called a follow bot I then reported the user I do not remember who but I do know they play bl2

I got banned from a few channels who claim sexism isn't a two-way street and proudly bashed one gender over the other. I don't want to listen to those kinds of people, but it hurts that the world has devolved into hate bile. I at least would like to see a list of channels that banned me so I can share it with people that may not be so wise to their ruses.

I got banned from a chat and the streamer told me to kms but I cant find it. This would be useful

I would like this feature, as I got banned from a channel some time ago, but can't remember what channel it was.

The idea is great, but James is right. Most of the users on twitch won't receive a lot of bans, BUT, and this might be very useful: if you're account got hacked (so did mine), and you randomly find out that you're banned in a channel you watch from time to time, it might be quite useful to have a tool that tells you if you're banned somewhere else, too.

this is a fantastic idea. I am only a troll when drunk late at night. I regret that I have received a ban or two or three. Since I am usually pretty drunk when it happens, I have forgotten the channels im banned in. Honestly, I just would like to see which ones for my own sake. Maybe go back and make reparations.

I feel like if someone who's been banned from a lot of channels had a list, it would become a sort of "hit list" for them to make new accounts to troll. :/

I can see this as only being useful to people who are frequently banned from many chat rooms. Most well-behaved users on Twitch don't receive chat bans, and in the rare instances that they do, they could probably easily figure out which 1 or 2 channels that they need to send a polite message to, requesting to be unbanned.

So basically, it's mostly only toxic users (even trolls) who would benefit from a feature like this.