Hi.
Since you loaded it from itch.io it might of changed all the settings to default (including the graphics quality)
If that did not help, when you open itch.io software try launching the game from the game folder instead of pressing the Launch button in itch app.
You can open the executable folder by pressing the "Show local files" under the launch button (In the itch app), try it from there it might work?
Hope it works out, if not please let me know. I'll be looking into it anyways.
Sorry about that.
Thanks