Suggest `-XScopedTypeVariables` with an out-of-scope type variable

Given the setup of

{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE ExplicitForAll #-}

import Data.Data (Proxy(Proxy))
import GHC.TypeLits (symbolVal, KnownSymbol, Symbol)

both

class Foo f where
  whatever :: Proxy f -> String

data Bar (s :: Symbol)
instance KnownSymbol s => Foo (Bar s) where
  whatever _ = symbolVal (Proxy @s)

and

whatever :: forall s. KnownSymbol s => Proxy s -> String
whatever _ = symbolVal (Proxy @s)

fail with [GHC-76037] Not in scope: type variable ‘s’

I think it would be sensible to suggest enabling ScopedTypeVariables here. The only other place where the extension is suggested is when type signatures occur in patterns.