This is a really rare (3 examples) tag, and it seems like it might need to be changed to one of the other tags that's more common. I was trying to remember the various tags like cleft of venus and vulva and so on, and came across this one. Isn't this an obsolete/incorrect tag?
https://e621.net/wiki_pages/23766 Tag def
From Google:
mons pu·bis
/ˈmänz ˈpyo͞obəs/
noun
noun: mons pubis; plural noun: montes pubis
the rounded mass of fatty tissue lying over the joint of the pubic bones, in women typically more prominent and also called the mons Veneris.
Updated