As the title says, after "upgrading" to Catalina, every once in a while an app would open automatically after login. These apps are not in Login Items and are not set as Open at Login. It doesn't happen all the time, and typically the apps are among the last ones being used before shutting down the machine. This has been discussed before here at Ask Different and at other sites, e.g. here and here and also here, but there doesn't seem to be a solution. For me about the only one of the suggested solutions (besides reinstalling) -- running First Aid in Disk Utility didn't help.
How one could fix this besides perhaps clean install (which was also reported not to work)?