Unsurprisingly, shitposter.world is actually a lot more widely fediblocked than my own instance. Heh. Weirdly, my own server, tkammer.de / pl.tkammer.de is even more widely blocked??? It was literally just me on there lol. If I had to guess: It must have ended up on some lunatic's blocklist that people apply to their server because they erroneously believe it's a sensible blocklist.