The Notes app on Big Sur won’t stay quit. It opens itself, so I quit it, and 15 seconds later it is open again. I’ve checked to see if something like Reminders or other app is automatically opening it. Not happening. Or if there’s a keyboard shortcut that’s launching it . Nope. Notes is not a login item. In fact I rarely use Notes.
Do you happen to use any Alfred workflows that searches Notes? Same thing was happening to me until I noticed an Alfred workflow was triggering Notes to open.
Good suggestion, @richrossi. I check and there was no workflow in Alfred that invokes Notes. Although I think there’s something like your suggestion going on. Some macro or reminder process or similar is keyed to open Notes.