[seagull]

(Disclaimer: I left FB several years back, this may not be completely accurate today. However, I would be surprised if this in particular has changed.) I worked on this system. Account deletion is a completely separate process from content deletion. The latter can in some cases just mark data as deleted or ready to be garbage collected, but the former actually deletes everything associated with an account. There are some nuances that are hard to explain well in front of a bunch of Senators though: your messages to other people will still stay in their inbox, it's not feasible to purge backups so there are tapes with your data around for several months. Also, derived data (ML models, etc) trained with the account data sticks around, although this isn't really identifiable info.