Didn't the EU antitrust entity explicitly allowed Facebook to buy Whatsapp only on the condition they never use Whatsapp data for commercial purposes on Facebook?
Interesting, after a quick search it seems you are right.
Facebook tried to extend data sharing in Europe in 2017 and got fined on the grounds that it was contrary to the E.U. merger rules [0]. So they seem to have learned their lesson, for now at least.