Former Facebook wanker, who worked in research. 1) we were always told and legal always pushed back hard on anything face detecting.(ie haar cascade "this is a face" let alone actual this is dave/sally) 2) the FTC would audit us to make sure we weren't doing that kind of stuff 3) all of the research prototypes had inbuilt/inline face removers up until 2024(I left after that so I don't know when/if that changed) 3.1)…
I recall that Facebook asked me to identify faces of my friends in order to "verify" myself about 15 years ago. Do you know whether Facebook still stores that data?
Honestly I couldn’t answer that. I never really touched production userdata (mainly because it was scary and also it was in PHP or some horrid transpiled interface to PHP)
My gut feeling is that facebook doesn't throw data away unless its forced to. So its probably there on your graph somewhere.