And correct me if i am wrong, but banning a user just stops them from posting, but i thought it did not delete their post history without additional mod action - which i cant see in the modlog

There’s an option when banning a user to also remove their content, albeit unless it’s an admin action I don’t think it would affect their whole post history beyond the specific community.

I’m kind of getting the sense as I look into this that it may be related to how Voyager is rendering the thread, as I’m not able to observe what’s being described from the web interface. That’s another catch in all this, the other apps and interfaces have their own quirks in how they handle rendering things, which itself is typically related to how they work off the base software (Lemmy in this case).

Edit: why am i forced to upload a photo for a new post?

Which way are you posting? Mobile/web interface? Shouldn’t need to add an image to post…

That aside, regarding your main question:

I think it’s very confusing when a single post appears with different comments on different instances, and have no idea how this works.

A basic reason for the difference in which comments are appearing across different instances/sites is because of delays in networking (federation) between the sites due to a variety of reasons. One of the common ones with the fediverse tends to be the software itself, and sometimes differences in versions’ federation handling. In this case it’s probably because Lemmy World is still running an older version of Lemmy with clunkier federation at Lemmy World’s scale, which causes delays in activities on there updating elsewhere (particularly those hosted in Australia).

Edit:
See also Kichae’s comment for a more detailed explanation, covers how things operate under more ideal conditions.

Sort of, it’s because a lot of microblogging software doesn’t have the same post format with title/post body. The current workaround for microblog to Lemmy and similar is to format it like this:

first line title

second or more lines post body

@communityname@site.name

#hashtags if desired

Appreciate this post OP, as I’ve wondered similar at times when not wanting to fuss with another machine for self-hosting (as often it’s not the case that I could run the server software on my main system).

Well, also maybe Reddit, unless they’re also removing/burying other social sites. Besides that, any messaging services one may use to chat with friends or others.

Echoing this, with some slight adjustments:

Promote the specific sites/communities to people, and on sites that permit it, share links back to specific posts/comments that you found interesting/amusing/etc. from said sites/communities.

Reddit got popular off the back of changes to Digg and people mentioning/sharing stuff from Reddit there. I’d imagine TikTok also grew in popularity from people sharing stuff from it on other major platforms like Instagram/YouTube/Snapchat/Twitter, much as now RedNote’s growing in popularity from people mentioning it on TikTok and other platforms.

At a glance, Misskey and associated forks may appear to be Twitter-clones, but dig a little more and you’ll find they’re a lot more, for better and worse.

The interface is highly customizable, not just with some different colored themes nor a multi-column interface, but that you can stack page elements in columns and set up “antennae” or filters to surface posts including specified keywords and/or hashtags while excluding others via keywords/hashtags as well. There’s also what they call “channels” which I think are sort of like groups or dedicated topics apart from hashtags to post to and discuss whatever the channel topic is.

Oh, and because it seems *key wants to have a little of everything, there’s Pages, which is basically longform blog posting, and some versions include simple games. There’s also options for some other widgets I’ve not mentioned here. It’s genuinely pretty wild compared to the other federated microblogging services with how much flexibility it has and all that it has packed in.

I think the only other federated service I’ve found that’s comparable in flexibility may be Hubzilla, albeit I got the impression it’s less user friendly, but still, very customizable and a lot you could do with it.