I believe it's related to the adjustment mentioned in Announcing the June Version Update (2021), so probably regular monsters in those areas.

That said, in July they adjusted Vanasarvik and Brekekekex, which are Voidwatch related monsters... so... I dinnæ know.

I'll need to go digging a bit more to remember what exactly this "level adjustment functionality" might be, but I kind of remember something like that from when Adoooulin was first introduced.