By the way, I found several forum threads where I had similar “symptoms”, for example,
@jaenders97 HDMI Screen doesn't wake up after automatic screen off. Nvidia Wayland (Fedora 41 KDE)
@ac10n When I turn on a TV connected to HDMI, it does not show in list of displays unless I restart
@joesh-00 KDE: How can I run kscreen-doctor on startup before login (to disable my external TV screen from showing login dialog)?
@monkesle KDE F41 - One of my two displays freezes after an hour or two
and many others…
Thanks @theprogram for the replies, but I thought about it and decided to leave the topic in this section, in my opinion, “off-topic” is a more appropriate place, since no common solutions were found earlier.