HasField with QuantifedConstraints

Steps to reproduce

data Foo a = Foo { a :: Int }
data Bar where
  Bar :: (forall a. HasField s (Foo a) Int) => Proxy s -> Bar

This throws a compile-time error:

Illegal instance declaration for ‘HasField s (Foo a) Int’
        Foo has fields

Looking at TcValidity.hs, it seems like this error is thrown when manually defining instances, which is not relevant to me (at least, it could be doing it under the hood). I'm not sure if this is even allowed, but if it's not, the error message should be better.

Expected behavior

Either work or provide a more clear error message like "A HasFields constraint cannot be used with QuantifiedConstraints".

Environment

• GHC version used: 8.10.7, 9.2.1

Optional:

• Operating System:
• System Architecture: