When starting up the RPI4 the HDMI 1 screen covers max 3/4 of the screen. The screen on HDMI 2 is normal.
I found that using desktop preferences, and set it to "strech to cover screen" again, but this will not help without switching the menu bar position to Bottom and then back again to the Top.
Now the screen is normal.
How can I overcome this once and for all ?