Thanks, that encouraged me to try again filter-brightness-simple. No problems this time.

EDIT: Nope, reported too early. After a while (longer time no usage) blank screen happened again. I have to go back to filter-brightness-als. That sucks.

Noticed also that there were new mce.ini in /etc/mce directory, mce.ini.dpkg-dist. I suppose this is a new one which has not been taken into use because old mce.ini was edited. Can anyone confirm, I don't remember whether that was there already before PR update.

I took that one into use, it seems to contain different color profiles.