There is a third issue we are aware of (`cabal update` is not run? · Issue #203 · haskell/actions · GitHub), manifesting in CI with a cache, namely that due to XDG backward compatibility behaviour it’s safer to perform cabal update after cache is restored, not before.
All the three issues will probably be addressed in cabal 3.10.2.0 (at least via explicit recommendations in release notes, perhaps via fixes), but at this point we don’t know the details yet, so for the time being we offer workarounds and gather feedback.