SUMMARY
With my laptop, I switch from single-screen to dual-screen setup and back at least daily. When the external screen is connected, I want all windows to be moved to that screen, since it is used as the main screen. (The laptop screen is turned on only for the rare case where I need some extra screen space, and to work around https://gitlab.freedesktop.org/xorg/xserver/-/issues/948.) That used to work fine up until Plasma 5.21, but with Plasma 5.23 is stopped working, meaning I now spend a bunch of time each day to move windows back and forth, which is quite annoying.

STEPS TO REPRODUCE
1. Connect the external screen and configure it to be on the left of the internal screen, and make the external screen primary.
2. Disconnect the external screen. Have some windows open on the internal screen; some maximized, some not.
3. Connect the external screen.

OBSERVED RESULT
The non-maximized windows move over to the external screen (presumably because they remain at screen coordinate [0,0], and since the external screen is on the left, that coordinate is on the external screen). However, all the maximized windows remain on the internal screen (meaning their screen coordinate changes since the internal screen is 1920px to the right).

EXPECTED RESULT
All windows should move to the external screen. This is what happened in earlier versions of Plasma/kwin (up until 5.21, I did not test 5.22).

SOFTWARE/OS VERSIONS
Operating System: Debian GNU/Linux
KDE Plasma Version: 5.23.0
KDE Frameworks Version: 5.86.0
Qt Version: 5.15.2
Kernel Version: 5.14.0-2-amd64 (64-bit)
Graphics Platform: X11
Processors: 8 × Intel® Xeon® CPU E3-1505M v5 @ 2.80GHz
Memory: 31,2 GiB of RAM
Graphics Processor: Mesa Intel® HD Graphics P530

ADDITIONAL INFORMATION