Polybrush increases APK size in an unreasonable amount

Hi,

I'm using polybrush to paint vertex colors to my meshes. Doing so increases my apk build size a lot more then expected.

For a mesh with 4000 verts adding vertex colors and thus switching to a polybrushmesh increases my build size with close to 400 kb (per mesh)

Adding vertex colors in 3dsmax beforehand to the model adds 10 kb which seems more correct (4 bytes/vertex). Where does these extra 390 kb come from. Working with mobile size will eat up very quickly this way.

Any ideas what i'm doing wrong here?