inconsistent full screen mode

On a Linux dual monitor configuration full screen mode works inconsistently. The Window size approximates the size of one monitor but is a little wider. Same while the space for score view obviously isn't recalculated. As a result when editing the cursor runs out of the visible part within the window.
My config:
OpenSuse Leap 15.5 with KDE-Plasma 5.27.9, Wayland
monitor sizes: 1024x1280
screen size: 2048x1280
usually preferred window size: 2 score pages visible (about 1600 px window width)
Effect:
minimum manually adjusted window width: 1051 (with correctly calculated space for scores)
full screen mode window size: about 1037x1280 on the monitor without menu bar
When entering full screen mode from small window there's no problem. The cursor stays on the screen then. But when entering from dual page half of the space where the cursor can reside is invisible.
This bug exists for several years by now.