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
A bit of social media history on this topic. Since Reddit is the big topic this month much like Twitter was 6 months ago…
10+ years ago, Reddit was a place that had communities like that for years. CNN story from 2012: https://www.cnn.com/2012/10/18/us/internet-troll-apology/index.html
Back then, 800,000 subscribers to community/subreddit, those were big numbers. It was part of what made Reddit what it is today, starting out with communities that Facebook wouldn’t allow. The owners of Reddit even gave that guy an award: Reddit gave him an award – a gold-plated bobblehead doll “for making significant contributions to the site.”
What seemed to shut it down more than anything was loss of anonymous usernames (the guy who created the subreddits got fired from his job). Today in 2023, it would probably be more like governments (hard to say, as the CNN story doesn’t say they found evidence of illegal images)?