Q: Annoying pop-up

Might be a cookie issue...

From your Safari menu bar click Safari > Preferences then select the Privacy tab then click:  Remove All Website Data

Quit then relaunch Safari and try Facebook again.

Other items can be at play where pop-ups are concerned, additional involving Safari:

• Stop pop-up ads in Safari - Apple Support:

https://support.apple.com/en-us/HT203987

And there may be items not related to Facebook app -- if there should be

an adware or other cause of the problem, as indicated by the earlier post.

Good luck & happy computing!

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