For example, I’m on Lemmy.sdf.org and I joined the Apple@lemmy.ml community. But there are many missing articles and comments. If I browse directly on Lemmy.ml for the same article there ~90% of comments are missing.
https://lemmy.ml/post/1152794 has 26 comments https://lemmy.sdf.org/post/11232 has 0 comments
I think there might be more going on as the post in question is 4 days old, and all the comments are at least 1 day old; is the syncing typically days behind? The federated version that OP links shows 0 comments, and the version on my instance has just 5 comments.
Is it to do with when a user on the remote instance first interacted with the post? I.e, its only showing comments from after someone on lemmy.sdf.org first interacted with the post?