The issue still exists today (09/30/2024) with the most up-to-date kde (6.0.5). I guess sometimes kde mess up its own configuration after waking from sleep, and by deleting ~/.local/share/kscreen, rebooting and reorganizing the screen, everything goes back again.
KDE 6.0.5 is 4+ months old. Don’t report issues on old version. Switch to Testing or Unstable branch, no issues.
//EDIT: 6.1.5 is now in Stable branch, just update the system.
@linux-aarhus why did you lock the thread and talk about Plasma 5?
because the thread is about - literally in the title - KDE 5.26
Initially the bug appeared on KDE 5.26 yes. But apparently the bug came back on KDE 6, and the guy searched for a thread about the issue, found it, and replied to it, which is what we expect from users, and a new user just did that (which is kinda amazing), and you lock the thread 
Good enough, you made a new thread now.
Are you using Wayland?
I seem to recall this is a bug with kscreen (it probably hasn’t yet been updated to Qt6). Try entering the following (in the terminal) to see if you can reproduce it.
This is taken from my scribblings a few months ago:
kquitapp kded
kded5
This will restart the kded5 daemon, and kded5 will load a kscreen plugin that reacts to hardware conditions like suspend.
If the same issue is generated then it’s a KDE issue, and queries should best be directed upstream:
I hope this helps. Cheers.