Do you mean Facebook Messenger ?
So far after the most recent updates my Facebook Messenger appears to be working as it should.
Please do check your notification settings / preferences.
You could also try Settings > Apps > Messenger > Storage > Clear Cache.
If I can be of any further help then please don't hesitate. Take care. 😎
Daily Driver > Samsung Galaxy s²² Ultra 256Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help. " This is the way. "