Can't exactly tell from where anymore since I've taken a few months of a break from gamedev until I picked this back up, but I remember it was called "10000 google english" or something on github and I made my own lists with that.

If a letter is not in the word it's just not highlighted, like in the regular wordle.

Not sure what UI bug you mean but I have observed the entire window having less width on Windows 11 for some reason even though it's a static fixed number. Not sure what's going on there but I'll have a look, thanks for the feedback!