Hi,
I have very little knowledge here, i mean with Android and iOS, but
Wird die Tastatur schwebend eingestellt, tritt der Fehler nicht auf ! ( äußerst merkwürdig).
This, for me it make sense that resizing the form due the appearance of the keyboard has something to do with the crash, try to record/log the series of the event from TEdit having focus and the visible form triggered Resize event.... or similar event that has to do with resizing, but this is more like shooting darts in the dark.
Most importantly, try to log the exact
exception message and call stack, it will help a lot in diagnosing this.