I have the Hide Adult Content checkbox selected in my profile settings, but I am still seeing stuff like this in the sidebar as links to Random Magazines / Posts / Threads.
I'm not sure if it technically is a moderation issue where the Magazine, Post, or Thread needs to be marked as NSFW in case the OP didn't do so or something more. It seems like it happens too often to just be where it is simply posts that slip past the mods so that makes me wonder if the NSFW checkbox is broken or just doesn't do anything.
It is only a guess, but my guess is this originated on the LemmyNSFW instance. Ideally they would mark everything NSFW, but some things over there don't get marked, and Lemmy doesn't have an option so the admins can set/flag the whole instance and all content.
This has been noted as a problem before, LemmyNSFW is certainly running the risk of being widely defederated as a result. I think Ernest is suggesting he'll code something into kbin so that anything which originated on that instance can (and will) be treated as NSFW regardless of whether the users over there identified it as such.