I’m trying to figure out how to get the comments of a post given a link to it using ActivityPub.

Based on reading the ActivityPub spec, I thought comments were federated via the replies key of the ActivityPub Object.

This works for Mastodon posts, but not for Lemmy (nor Pleroma). As an example

curl -H "Accept: application/activity+json" https://lemmy.my.id/post/79514 | jq

doesn’t contain a replies key. Yet the comments are federated to Mastodon somehow.

What is going on? How can I get the comment?