Actually I just got the desktop notification again. It is ridiculous:
"Pending update of "firefox" snap. Close the app to avoid disruptions (12 days left)"
WTF are you trying to say, Ubuntu? Of course closing the app doesn't trigger the update, so I will RTFM later today how to get rid of this annoyance, or reinstall FF with apt this time. @lutindiscret sent a good guide of doing that quickly enough ?