There is a glaring loophole in chat history logging that has been present for years since the chat logging system started. It involves changing your name via Twitch's name change feature. Once someone has changed their name, you can no longer reliably pull up their entire chat history. It is effectively halted for the old name, and wiped for the new name so long as you do not have their original name.

I'll try to explain this as simple as I can.

Let's say I have actual years of chat logs under the name "desertp" on "examplechannel"
https://www.twitch.tv/popout/examplechannel/viewercard/desertp?popout=
All of them would show here for a moderator, right? Right. Years of logs since the system was implemented. Everything is there. This is Good.
Now..
Let's say I then change my name to "dezartp" via twitch's name change system.
https://www.twitch.tv/popout/examplechannel/viewercard/dezartp?popout=
All chat logs are totally gone, even if its the same account. It's as if this user never existed before.
Why is that?
This is because Twitch is pulling data not from their established userid, which is like a series of numbers, which is a universal indentifier outside of the actual username, but only pulls directly from the name itself -- which is superficial.
This basically is a loophole that allows people to erase their entire chat history, so long as you don't know what their original name was, and cant prove they were their old name -- and it becomes a tiresome process of trying to figure out someone's identity that may be causing problems and abusing the system to change names to obsfucate their information. It's a headache that could be very easily fixed by tying a user's chat history to their userid, and looking up any of the names associated with said userid pulls up all their messages. You don't even need to reveal the userid to do this, you could mask it.
I'm not sure why this is like this.
Basically, when I want to look up someone's chat history when I am modding to determine if this person is a problem for the chat, especially in large chats that go very rapidly and it's hard to keep track of people, it would be extremely helpful to see all of their chat history tied to that account's user_id.

Obviously if someone changed their account completely, that's another issue entirely, and a lot more rare. Most of the time this is about people just changing their names, and sometimes it's not even done maliciously either. It's just annoying to keep track of who is who and their history when they can just wipe it clean every month. Some people change their names very very often and it makes them hard to keep track of. There are some communities where this is a problem more than others and it would be a heavily appreciated change to how chat is logged.