How is this distinguishable from spam? It's a random vendor sending you an RCS message. It's not the app serving ads, it's doing its job displaying the message.

Deleting the Messages app for this is the same as deleting your email client in a bid to reduce spam.

I'd need to see proof that android has anything to do with it. It's just a vendor sending you a RCS version of marketing messages. If they have your phone number they send you the message, google or not.