Kubuntu 21.04
Asserting that correlation != causation right up front, but it does seem suspicious.
I installed PCManFM 1.3.2 and it's everything I want in a file manager I use for FTP, namely: it downloads files to consistent folders that match the online structure, and doesn't prompt me to first upload and then overwrite remote files when I make changes -- it just DOES IT.
However, after I installed it, suddenly Task Switcher, set for MRU, just seems to switch randomly between windows. I've been through all the settings I can find for both apps, but haven't found anything useful.
I've considered uninstalling it just to see, but I'd rather not if it can be avoided, hoping that someone's encountered this before and might have some direction.
Any ideas? Places to look..? Is there another file manager that operates the same way?
EDIT: NOT random. It skips the app it should go to. With windows 1, 2, 3, 4: working in windows 1 and 2, Task Switcher skips 2 and goes to 3, then 4. I have to switch all the way through the stack to get window 2.
EDIT: uninstalled PCManFM; rebooted; worked for a day, Alt+Tab works as it should; re-installed PCManFM; rebooted; Alt+Tab broken again.