I hate to admit it, but a local "Cause" required me to get a Facebook account if I was going to join the rebellion.;D. Quite by accident, I became one of the ringleaders, and get more than my share of messages.
Recently, whenever I open FireFox, I've been getting those little pop-up notices about being messaged... Even if I DO NOT have a tab open to a Facebook page.
Did Facebook install something on my browser (or elsewhere) that doesn't show in the add-ons list, nor in the installed programs list?
See if this helps: Web Push notifications in Firefox | Firefox Help (https://support.mozilla.org/en-US/kb/push-notifications-firefox).
Personally, I have my privacy settings locked down in Facebook and also use F.B. Purity (https://www.fbpurity.com/) which blocks the garbage I don't want to see.
Thanks: Privacy on FB isn't easy.
I was also using FBP, but it wasn't helping on that particular annoyance.
I made the browser changes suggested by Mozilla. We'll see how that works out.
Got a message without a pop-up nagging me about it.
So far, so good ;D
Excellent! That hasn't happened to me, fortunately since I'm one of the moderators of our town Facebook group with over 9,400 members. I'd be inundated with notification pop-ups, especially since we approve not only each member but also each new post.