Missing Enum instance for IoSubSystem

Hi all, In ghc 9.12-alpha the Enum instance for IoSubSystem no longer exists. I don't see this change mentioned anywhere in the docs (release notes/changelog) here: https://downloads.haskell.org/ghc/9.12.1-alpha1/docs/users_guide/9.12.1-note... Was this change intended or was it a refactoring issue? The datatype itself was moved from GHC.Internal.RTS.Flags to GHC.Internal.IO.SubSystem. The enum instance was earlier defined in GHC.Internal.RTS.Flags but now isn't defined in either of the modules. Best, Adithya