There are multiple reports of this. Dont let anyone tell you you are crazy. 
( Exhibit A: Update icon not reset after updating flatpaks )
They may or may not be more particularly tied to flatpak and/or gnome … but I believe there have been KDE reports as well.
I wouldnt know because pamac is banished here, and even if it werent, such a notifier certainly would be. 
But for folks that do use it, or develop it, it would seem these are bugs to be squashed.