I believe that detection works for posts in the same community too. I posted two same links in a community and both was detected as cross-posted:

• https://lemm.ee/post/31756832
• https://lemm.ee/post/38772950

You can get the cross posts via API resposne. See cross_posts field in the response of https://<instance>/api/v3/post?id=<ID>.

Oddly, the endpoint on lemm.el and lemmy.ml return comments:

> curl 'https://lemm.ee/api/v3/comment/list?post_id=45734814' | jq '.comments.[] | .comment.content[:50]'
"Yeah, you're right. I didn't read enough of the do"
"Thank you for the tip ... but whatever I try with "
"~~In 0.19.5, they removed the deprecated `post_id`"

> curl 'https://lemmy.ml/api/v3/comment/list?post_id=21766749' | jq '.comments.[] | .comment.content[:50]'
"Yeah, you're right. I didn't read enough of the do"
"Thank you for the tip ... but whatever I try with "
"~~In 0.19.5, they removed the deprecated `post_id`"

I think it would be better to ask the admin of the instance before creating the issue.

You can get 50 items at most with limit=50. Try

https://lemmy.ml/feeds/c/lemmy_support.xml?sort=New&limit=50

Not a direct solution but GET /api/v3/site may help.

Maybe some rules in nginx.conf has been delegated to nginx-internal.conf.

I suspect your instance was used to backup the original communities.

You shouldn’t post the auth value here - it works like a username and password.

I grepped the source and found

• https://github.com/LemmyNet/lemmy/blob/0.18.2/crates/apub/src/objects/post.rs#L53
• https://github.com/LemmyNet/lemmy/blob/0.18.2/crates/db_schema/src/schema.rs#L645

Can you run the code against another instance, and curl https://lemmy.ml/api/v3/post/list?