I prefer to merge this early in the 3.10 dev cycle, to increase chances of getting early user feedback if this change breaks 3rd party applications.

Thanks for the review @methane. Usually, features require 2 Python release to be removed, with a deprecation first. But this specific case is really weird. I chose to remove it immediately. IMO it was exposed in public "by mistake", whereas a private attribute would be enough for internal usage.