Strange title as AtlasObscura haven’t actually revealed anything; they’re almost as prudish as the original Victorian discoverers.
Judging by this[1] less prudish source, it doesn’t even seem THAT shocking. There’s a lot of ‘normal’ fresco and only a few pieces of the cheeky stuff…
[1] https://news.artnet.com/art-world/pompeii-reopens-house-of-v...