Core Lint error with -O2 in containers' sequence-benchmarks

I originally reported this in #17722 (comment 248156), but it seems less related to that issue than I initially thought.

From this benchmark I have extracted this reproducer:

{-# language ExistentialQuantification #-}

-- | This code is extracted from containers' sequence-benchmarks and the gauge
-- package.
module M where

import Control.Exception (evaluate)

data Benchmarkable = forall a .
    Benchmarkable
      { allocEnv :: Int -> IO a
      , runRepeatedly :: a -> Int -> IO ()
      }

a, b :: Benchmarkable
a = nf (\(s,t) -> (,) <$> replicate s () <*> replicate t ()) (100,2500)
b = nf (\(s,t) -> (,) <$> replicate s () <*> replicate t ()) (2500,100)

nf :: (a -> b) -> a -> Benchmarkable
nf f0 x0 = Benchmarkable (const (return ())) (const (go f0 x0))
  where go f x n
          | n <= 0    = return ()
          | otherwise = evaluate (f x) >> go f x (n-1)

≻ ~/src/ghc-head/_build/stage1/bin/ghc -dcore-lint T17722-gauge.hs -O2
[1 of 1] Compiling M                ( T17722-gauge.hs, T17722-gauge.o )
*** Core Lint errors : in result of Simplifier ***
<no location info>: warning:
    Out of scope: $wf0_s23v [InlPrag=NOUSERINLINE[2]]
                    :: Int# -> Int -> [((), ())]
                  [LclId, Arity=2, Str=<L,U><L,1*U(U)>]
    In the RHS of $s$wpoly_go_s26H :: State# RealWorld
                                      -> Int# -> (Int, Int) -> (# State# RealWorld, () #)
    In the body of lambda with binder sc_s26z :: State# RealWorld
    In the body of lambda with binder sc_s26y :: Int#
    In the body of lambda with binder sc_s26x :: (Int, Int)
    In a case alternative: ((,) ww_s23o :: Int, ww_s23t :: Int)
    In a case alternative: (I# ww_s23r :: Int#)
    Substitution: [TCvSubst
                     In scope: InScope {x0_X2 f0_aEB x0_aEC $krep_a1TC $krep_a1TD
                                        $krep_a1TE $krep_a1TF $krep_a1TG $krep_a1TH $krep_a1TI
                                        $krep_a1TJ $krep_a1TK $krep_a1TL $krep_a1TM allocEnv
                                        runRepeatedly a b nf $tc'Benchmarkable $tcBenchmarkable
                                        $trModule $trModule_s1Vs $trModule_s1Vt $trModule_s1Vu
                                        $trModule_s1Vv $krep_s1Vw $krep_s1Vx $tcBenchmarkable_s1Vy
                                        $tcBenchmarkable_s1Vz $tc'Benchmarkable_s1VA
                                        $tc'Benchmarkable_s1VB lvl_s1Zp poly_go_s1Zr x0_s1ZN x0_s1ZO
                                        b_s1ZP a_s1ZV lwild_s20a $wpoly_go_s22H $wf0_s236 ww_s23n
                                        ww_s23o ww_s23q ww_s23r ww_s23t go_s256 $wxs_s259 lvl_s25a
                                        sc_s26x sc_s26y sc_s26z $s$wpoly_go_s26H $s$wpoly_go_s26I}
                     Type env: []
                     Co env: []]

Full Core Lint error message

I can reproduce the issue with GHC 8.6.5, 8.8.2, 8.10.1-alpha2 and HEAD (a71323ff), but not with 8.4 and earlier.