Seems like the most plausible explanation. OTOH it feels like this is the sort of thing that might have been discovered/mitigated more quickly had there been a human in the loop.

OTOH one could previously pay an Instagram support contractor to do an account swap, so having a human in the loop allows for other avenues of exploit:

https://www.wsj.com/articles/meta-employees-security-guards-...

This still happens. Meta doesn't do much to protect against this, they just fire more people and hire new agents when they find out one was bribed.