strange inferred kind with TypeInType

This type family has a strange kind to begin with:

{-# Language TypeFamilies , TypeInType #-}
type family F f a :: a

But it gets even stranger when you ask ghci what it thinks about F:

> :k F
F :: * -> forall a -> a

There is a forall which doesn't seem to bind any variables and hasn't got the customary delimiting dot.

Trac metadata

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information