Slackware-current 64-bit
System update: 6/16/2022

After update laptop monitor setting are screwed up: after login screen is very dark. It flickers and then it goes dim.

Only way to fix this it set brightness in the settings.
However brightness settings on AC power are 70% and screen is still very dark.
If I move slider anywhere and back to 70%, screen is bright again. Unfortunately, after reboot monitor power settings are screwed up again.

Also I have different brightness when system is on battery. These settings do not work at all when unplugging laptop.

Above worked fine before today's system update.

Chances are you didn't review the new config files and select to keep any you have customized. They should still be there now labeled something like /etc/foo/foo.orig and are easily restored.

Thank you enorbet but no, I did not see a prompt regarding new config files.

Chances are GKH and co screwed up another kernel release, it took them a month to fix a nasty usb bug a year ago, OP might want to track downthe previous kernel set and install it, I think Tadgy has a server of them but I forget the URL.

I think that this is an issue with plasma. I still have 5.17.13 installed. So I just rebooted to 5.17.13 and nothing changed: when plugging/unplugging laptop, screen flickers, but brightness does not change.

It sounds like it could be related to this urgent powerdevil bugfix: https://invent.kde.org/plasma/powerd...ecab6c7857cb89

Thank you, I hope that this is it and fix will correct the issue soon.

Recent update fixed the issue