wanted

As for mastodon you have to search communities with their name but replace ! by @ as if it was a username ([email protected] becomes @[email protected]).

I think that it has to do with lemmmy and instances. When no one has searched for a specific community from your home instance this community isn't known by your instance. To find a niche community that wasn't known by your instance you must use the exact name of this community (like [email protected] for exemple) to find thoses exact names and brosse all communities you can use lemmyverse.net