Not sure if this is an issue with GrapheneOS - but I only noticed it after the recent OS update.
When a Signal message comes in, I get a floating conversation bubble (normal).
When I go to type on the bubble, my keyboard (Heliboard) pops up (normal).
But the keyboard covers the lower half of the bubble so I can't see what I'm typing (abnormal).
Has anyone else experienced this? Is there a fix?