> Any webpages embedding facebook/twitter/microsoft/google trackers have already deanonymised you

I bet OP has already blocked at least 3 of them. Private browsing is only a partial solution, blocking/unblocking domains, scripts, etc. on a case-by-case basis is a more reliable way to defend your right to privacy against abusive practices (I'm talking about fine grained adblockers such as uMatrix/uBlockOrigin) daily.

I admit it can be a hassle sometimes, in particular if one explores the net every day, but staying away from bad actors (such as some of those 4) is one way to maybe eventually stop them - even if "vote with your clicks" feels as pointless as "vote with your feet" when you're just one in many millions.

How well do those 4 trackers track you if you don't have accounts with any of them?