Only Lemmy.world and Lemmy.ml got defederated as far as I know. I see you’re not on one of those, so you can still see and participate with them.

I only use ethically sourced, farm-to-table instances.

IAMA was the subreddit that hosted AMAs.

Both acronyms come from the titling format: “I am a XYZ, ask me anything”

Not just you. Personally I’d rather not see them at all, if all they’re doing is tagging the community. I think that’s more of a Lemmy issue as a whole, though.