They made a announcement here on Lemmy https://lemmy.world/post/3234363

The original was posted on discord. It was:

Removal of Piracy Communities

Earlier today, after review, we blocked and removed several communities that were providing assistance to access copyrighted/pirated material, which is currently not allowed per Rule #1 of our Code of Conduct.

The communities that were removed due to this decision were: !piracy@lemmy.dbzer0.com, !piracy@lemmy.ml, !steamdeckpirates@lemmy.dbzer0.com.

We took this action to protect lemmy.world, lemmy.world’s users, and lemmy.world staff as the material posted in those communities could be problematic for us, because of potential legal issues around copyrighted material and services that provide access to or assitance in obtaining it.