so apparently if a hacker compromises your google account, they can just make it into a "child" account managed by a "parent" account they control, and this completely takes away your ability to recover the account via a backup phone number or email address or similar
(since those require "parental approval" once an account has been made into a "child" account)
this has just happened to a good friend of ours
and it's a known problem and, of course, Google do not have support personnel you can contact
so you are just totally fucking screwed