[Mr. Jeeves]

According to u/ramenporn—who claims to be a Facebook employee and part of the recovery efforts—this is most likely a case of Facebook network engineers pushing a config change that inadvertently locked them out, meaning that the fix must come from data center technicians with local, physical access to the routers in question. The withdrawn routes do not appear to be the result of nor related to any malicious attack on Facebook's infrastructure.

Unintentional internal sabotage is the most effective kind. :)

[algore]

I will bet a large amount of money that the poor responsible network engineer is either in India, or has an H1b visa.

[AppyPappy]

A config change tested in production. Lovely