Why is facebook giving me notifications from 4 years ago???

This about the third time this has happened. It will say some commented on a post you were tagged in. And i get confused because people don't tag me in posts cause I don't know people and it turns out its from 4 years ago...😑

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freeflow · 70-79, M

I get those - thing is I'm not on Facebook, lol. When I check the url/email address that sent it, it's not from Facebook at all! Malware?