Unexpected variable untouchable inside constraint since GHC 9.8

Summary

With GHC 9.2.4 and GHC 9.6.2, this compiles:

{-# LANGUAGE GHC2021 #-}
{-# LANGUAGE QuantifiedConstraints #-}
module Main where

import Data.Coerce

satisfyConstraint :: (forall x y. Coercible x y => Coercible (m x) (m y)) => ((forall x y. Coercible x y => Coercible (m x) (m y)) => m a) -> m a
satisfyConstraint go = go

main :: IO ()
main = do
  satisfyConstraint $ pure ()
  pure ()

However, with 9.8.1, I get:

Test.hs:12:28: error: [GHC-83865]
    • Couldn't match expected type ‘a0’ with actual type ‘()’
      ‘a0’ is untouchable
        inside the constraints: forall x y.
                                Coercible x y =>
                                Coercible (IO x) (IO y)
        bound by a type expected by the context:
                   (forall x y. Coercible x y => Coercible (IO x) (IO y)) => IO a0
        at Test.hs:12:23-29
    • In the first argument of ‘pure’, namely ‘()’
      In the second argument of ‘($)’, namely ‘pure ()’
      In a stmt of a 'do' block: satisfyConstraint $ pure ()
   |
12 |   satisfyConstraint $ pure ()
   |                            ^^

Environment

• GHC version used: 9.2.4, 9.6.2, 9.8.1