Antitrust laws are based around competition. This behaviour is shitty, but not anticompetative. I'd look to consumer protection law (although consumer protection law on this stuff is pretty weak at the moment).
Iirc, antitrust can also apply to using your dominance in one area to shut down competition in another. I think that was the issue with internet explorer and windows, but correct me if I’m mistaken
That is correct, but in this case what is the competitor being impacted?
I am really looking forward to the revision of the GDPR and the overhaul of the one-stop-shop concept. Supervisory authority in EU will pool resources to discipline FB on a monthly basis. Irelands SA is as openly corrupt as Trump.