One of the instance that is promoted on join-lemmy.org is burggit.moe that is defined as “NSFW & Loli/Shota/Cub friendly”. Loli is legally considered as paedophilia in europe and the US, so even if it’s legal in the country that host the instance, I would suggest to not promote it as an instance to join
I don’t think it’s true that such things are illegal in the US at least, but yes, this one should be delisted.
If I recall correctly, as long as you can tell it’s not real it’s legal. But it’s still gross. It’ll be the first server that my instance is defederating.