privacy

Looked through the docs a bit and it's not really clear to me: I'm posting this on lemmy.ca, does that mean only that instance knows my IP? Or does every instance it federates with get my ip alongside this post?

This seems maybe important, did I miss a privacy guide to Lemmy someplace? Cursory searching didn't come up with much official. Are there other aspects we should be thinking about here? I'd come across some mention of deleted posts being still available everywhere they were sent but that sorta makes sense -- hard to "unpublish" anything.