I have two accounts on Thunder, one in lemmy.world, and one in lemmynsfw.com. I can see posts and communities just fine in my “all” view, but when I search on the search bar, even with the nsfw account set to active, no nsfw communities show up. Is this an issue with defederation? Or just a thunder issue where it won’t search nsfw communities?
You may want to check your account settings, when you register you can select something like “Show NSFW content”, there’s a related option if you visit your account settings as well (at least on web).