I've been looking everywhere for an answer to this, and only ever found one other topic in reddit where a person had the same issue, and they never got it resolved.

A couple of months ago, my Itch.io app suddenly would not load properly. It loads the app, but I get this tiny little window of what looks like part of the Itch logo?

I've tried reinstalling and even installing through the Epic launcher, no dice. I can't do anything to the window either, no options to maximize or anything.

This is what it looks like when I load it up:

It’s hard to for me to say exactly what is going on, but it appears that possibly the window got resized very small by something else on your computer, and then it’s trying to restore the app at that size when you launch it. Unfortunately, the easiest way to solve this may to clear your local settings and restart the app.

Hope that points you in the right direction