Surprise level: 0
I'm not sure how anyone expects any form of privacy from any company Under The Meta umbrella. I would be more surprised to be told that they weren't selling your data to every company that offered to buy it.
I would say this should be ruled out / illegalized but personally I've hit that point where I really don't think we're ever going to have any right to privacy in this country(US), and the government itself benefits far too much from the same privacy Outreach. It will just end up being a slap on the wrist or another pop up saying "Hey by using the site you agree to XYZ" or "by making this account you accept to give away your first born child". But considering the alternative is probably them making the service a subscription based, I'm expecting the majority of their users would prefer it this way.
That being said, Facebook's biggest push right now is all your chats are now end-to-end encrypted, so what this tells me is that either Facebook knew this PR was going to get out there and they wanted to do damage control early, or that Facebook is not doing true end-to-end encryption and that it's still server client encryption between both clients with Facebook holding the shared key.