It’s probably because you made an account on an instance that blocks nsfw. You need to make an account on a different instance that allows nsfw and does not defederate the particular instance you would like to browse. Or just make an account on the instance you care about the most.
Either way, another federation design decision to confuse the hell out of all its users.
Yes it does. Here’s a list with most important instances and their restrictions: https://github.com/maltfield/awesome-lemmy-instances