This is indeed a feature of Lemmy, activated by default
This issue was completed a long time ago, the slur filter is entirely optional, you can add one using the config: https://join-lemmy.org/docs/en/administration/configuration.html
https://github.com/LemmyNet/lemmy/issues/622
Lemmy.ca's admin probably never changed the default values. I noticed it a while ago too but forgot to notify it, thanks.
Edit: also don't bother too much with the other commenter, they have MAGA in their bio
Good to see we are back