The ability to create automod lists (similar to autohost lists) which would highlights users who have been banned in channels on your list.
Along the lines of the new restricted user function, a good tool for creators and channel moderators would be the ability to see users who have current bans in channels you may care about.
I.E. Similar to the autohost function, you could set a list of channels where you want to maintain similar moderation standards (this would be useful for communities such as NoPixel, content creator houses, and streamer friends, etc.). So Person A could put Friend B and Friend C's channels on their channel's automod list. Banned User 1, after being banned in Friend B and C's channels, decides to drop into Person A's channel. Upon doing so, in the Twitch mod view, the creator and moderators of the channel can see the user highlighted (similar to how first time chatters and monitored users are highlighted) with a message along the lines of 'This user has been banned in channel(s) on your automod list'.
To avoid compromising the privacy of any given channels moderation, the message wouldn't necessarily let you know which channel the person has been banned in, just that they have been banned in one of the channels on your list. Additionally, it could be made into an opt-in function on both ends, so only creators who have opted in to the function would be able to create lists/be put on lists.
This would make modding channels for creators who are a part of specific communities more efficient, and would further safeguard Twitch chat from any users who may create issues.