Unused import warning is order-dependent?

A1.hs

module A1 (astuff) where

import C  -- no warning!
import B

astuff :: Int
astuff = 10 + bstuff + cstuff

A2.hs

module A2 (astuff) where

import B
import C  -- warning: unused import

astuff :: Int
astuff = 10 + bstuff + cstuff

B.hs

module B (
    module B,
    module C
) where

import C

bstuff :: Int
bstuff = 100 + cstuff

C.hs

module C where

cstuff :: Int
cstuff = 42

haskell-import-order.cabal

cabal-version:       >=1.10
name:                haskell-import-order
version:             0.1.0.0
author:              Tom Smeding
maintainer:          tom.smeding@gmail.com
build-type:          Simple

executable haskell-import-order
  main-is:             Main.hs
  other-modules:       A1, A2, B, C
  build-depends:       base >=4.13 && <4.14
  default-language:    Haskell2010
  ghc-options:         -Wall

Main.hs

module Main where

main :: IO ()
main = putStrLn "Hello, Haskell!"