I'm subscribed to !selfhosted@lemmy.world, yet I never saw this post show up.
I can't find it with a direct search on lemmy.ml either but the instance is listed here.

Am I misunderstanding how federation works? Or is there a reason why this post is not available on lemmy.ml?

Looks like OP is banned by .ml

Which isn't uncommon and says nothing about OP.

.ml just bans people for stupid shit, you likely can't see any of their posts, or a lot of other people's.

The only solution is not having an account over there.

Didn't .World defederate from .ml?

OP can you see any .world communities or posts?

Nope, both Lemmy and piefed are still fed.

I agree but op is on ML. Which again says nothing about op. So it could be that a community is blacklisted or not synchronized.

The person who made this post is from .ml and made it on .world....

So no, it's a pretty safe bet they haven't defederated.

But .ml banned the person who's post this OP can't see, that's the reason why they can't see that one specific post. It's any post by an account banned by .ml.

Anywhere on the fediverse, that's why .ml bans so many people that never comment on .ml

They don't want their users exposed to certain things. And this is a way for them to control what a .ml user sees even on other instances.

Haha. Yeah, I should pay more attention. Thanks for explaining it slowly for me :)

Because iirc .world defederated from .ML. Hexbear too.

But OP's instance is ml

Defederating works only in the opposite direction. You don't see content from hexbear and lemmygrad on LW, as LW defederateted from these sites, i.e. doesn't fetch their content. It cannot inhibit the sites from fetching its content. For that they these would need to defederate from LW themself.

Also, LW didn't defederate from .ML, neither did .ML defederate from LW.
https://lemmy.world/instances
https://lemmy.ml/instances

Didn't .World defederate from .ml?

No. And if so, it would work in the opposite direction, a user won't see content from .ML on their site.

Yes, but the OP of the linked post on LW is from LW. So likely .ML blocks that particular LW user, i.e. doesn't fetch (or display) their content.

You're talking about two different "OP"s.

The OP of this post isn't banned on lemmy.ml, but the OP of the post that this thread is about (i.e. that can't be seen there) is: https://lemmy.ml/u/breadsmasher@lemmy.world

Ah, that makes sense. Thank you! I might eventually look into self-hosting an instance so I don’t have to keep migrating.