A lot of content reviewing, if not all, is outsourced to consultancy companies as far as I know. I used to work next to a building full of content reviewers in such an arrangement.
Indeed - having spoken to these reviewers as well they seem to have fairly minimal day-to-day involvement with the company themselves.
Just noticed this comment was flagged for some (probably automated) reason, vouched for it but it's a bit late.
Hilariously enough, most of the front-line moderators are outsourced, so it's even worse than you think.
I suspect those are not employees and not counted in this at all.