If I am posting this on the wrong place or missing something, give me a heads up :)
Video showcasing the bug: https://streamable.com/3jusbu
I'll add a link for a quick video I just took which I hope describes my problem for you. This bug happens randomly, makes it impossible to change apps, but I can swipe down and use the notification panel. I've also encountered another version of this bug, but then when I swipe up to change apps the app closes instantly. So if I work in two apps or go to the home screen, I have to reopen every app. One possible reason for that could be full storage according to google, which isn't the case. Any help appreciated, and let me know if you need more information :)