Sorry if this is the wrong category, but you make it as hard as possible to report bugs.
So after this patch was included in the qt5-wayland package (5.15.5+kde+r38-2 from the testing repos), all KDE applets and windows are now left-aligned, e.g. the start menu, loudness applet etc.
So I recommend to revert the version to 5.15.5+kde+r38-1 in the testing repo and to keep this version in stable and not update it for now.