[tgsovlerkhgsel]

> My current theory is there is some employee at Meta that's ultimately stealing the account.

This was my first thought given the e-mail address change. Someone e.g. bribing a support person.

My (uninformed) guess would be that given that you got the account back, this probably got escalated, someone looked at it, fixed it, and hopefully got the criminal support person's access disabled, until the next one gets bribed...