Grrrr, I would say "unbelievable" but it's not, it's Facebook.
FB messenger used to be for people you know to message you. Now it's turned into yet another way for FB to send people to your profile, open up group chats, encourage everyone in your group to message you and - yes - to send you ADVERTS in Messenger.
Now my phone is going PING every few seconds with more of this tosh. 

 @bade302b You still use facebook.. wow. 

 @bade302b PING for ADVERTS? WTF? This is ridiculous! 

 Okay I have trawled through my phone settings and the FB app settings, trying to turn off anything I can. I seem to have stopped FB notifications, I hope. But the FB settings are huge and so complicated no ordinary person is going to wade through all that lot.