Oretoises and stonelings spawn in huge quantities in the new alex's cave (candy cavity).

Idk if I should report this to alex instead of quark

This could maybe be because Quark doesn't respect the forge:no_default_monsters tag, which is an unofficial biome tag used by mods like Alex's Caves and Terralith. At the same time, I don't think Oretoises or Stonelings count as monsters, so I'm not sure.
I don't think they spawn in any other AC biomes, so my guess is that Quark has been going in and adding compat manually, with Candy Cavity being so new that they haven't gotten to it yet. Respecting that tag would probably be a good future-proofing method if that's the case.
Edit: I just looked into it a bit more, and Oretoises count as Animals, and I definitely don't think Stonelings count as monsters. I still think it'd probably be best if they respected this tag, though - there should probably be a tag for excluding generic mobs altogether, but in a vast majority of cases, no_default_monsters is gonna be used to preserve a biome's themeing, so I think it should probably apply to Oretoises and Stonelings.