I have had the same glitch happen once, a simple refresh fixed it for me.
I'm not sure what is causing it, I'm not doing anything special to get the keyboard state and I also never saw it happen on games that I host using github pages. This makes me fear it is a bug between the engine and itch.io.
If the issue persists, could you try https://lenscas.github.io/glitch_dungeon/ (Its the same build)? If the issue is still present there than it's something else. Otherwise, it will be on my list of things to check out at a later date :)