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
On Mastodon this kind of heads up are called #FediBlock and it’s useful to decide to block problematic instances together