Sometimes, if you're in chat, the game will think that the top left of the screen is being pressed down. This makes it impossible to do anything, and while you can still see things happen, you have to restart the game. Even if you somehow get out of the chat screen, it still thinks you're holding it.

This isn't a problem with my device, this happens to multiple people. It seems to happen at least once or twice a day.

I don't know how to reproduce it. It just happens, and it's really annoying.

I searched it and didn't find anything.

This probably only affects touchscreen/mobile but I really don't know as I don't know how to force it to happen.

(Edit: This is not the same as https://bugs.mojang.com/browse/MCPE-128485 - not even close)