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.