Byakugan01 said: IS there a reason the monstergirl_profile tag was deleted and replaced with a pool?
Makes it much easier to index them, for one thing. Also, it's pretty much standard pooling policy that if there are a lot of images by a single artist, and/or they are all made along a certain theme (e.g. a series of comics, or pixiv image-response series), they should be put into a pool for orderly indexing and such.
If you need to search for them, either remember the pool number (in this case, pool #2206), or use a combined tag search (i.e. kenkou cross monster_girl).