They run lemmygrad and are dedicated communists, as well as having a very opinionated "bad words" filter that's hard coded into the lemmy server software and not configurable without building it yourself.
Edit: commented below, but it looks like at some point they added the ability to customize the bad words filter as part of the site config, so that part doesn't currently apply. Early on there was a bit of drama about the original hard coded version though.