A lot of their security/policy work is hiring tons of humans to fix things. For example they are hiring an additional 10,000 content moderators. That will obviously impact profitability.
Just like Google, they are learning that AI is not up to the task of dealing with humans that try to game the system by all means possible.
I don't think neither companies ever denied that AI won't get 100% of the cases, they just say that you can't moderate billions of posts with human moderation alone, you need AI to take care of the 99%, and humans for ambiguous cases.
China has a huge staff of these people too. I think at last count they had 20,000 people employed doing content moderation for the country.
I would think it is much more than 20,000 in a country of 1 billion people with such tight content controls.