About the user script
If you're a streamer, you may have an interest in this script. It puts a clipboard icon beside the username in the viewer card that pops up when you click on a user's username in chat. Clicking the clipboard will copy the username to your clipboard.
This can be useful if you're watching a stream and see someone being toxic and you may want to pre-emptively ban them in your stream.
It will pop up an alert after the username was successfully copied to clipboard.
You'll need a user script runner.
Here's the script: https://gist.github.com/techygrrrl/d91ffac53520caf86e822fd1f9580aaa
Click the "Raw" button to prompt your script runner to add the script.