Google has not made an official statement regarding this but they have informed Blogger users that are going to be affected by this move.
Apparently, the company has decided to kill all blogs with adult ads on their Blogger platform. They have been given a few days to backup their data to migrate to another platform. The other alternative is to remove the adult ads.
A lot of hosting blogging solutions have had similar issues with monetization of adult blogs on their platform. The best alternative is to find a web hosting company that is comfortable with adult websites and use a self-hosted solution like WordPress.