I’m confused. It’s my understanding that when you have a new ATMOS mix on Apple Music, the stereo version ( which you get by turning off the ATMOS switch on the Apple Music app) is the new Stereo base mix of the material.Stereo streaming is the original mix. If you're in doubt, check The Song Is Over. The (newly re-recorded) synth is quite different in the second half of the song.
In the case of Who’s Next, in the pre release of the album, the main tracks were available as a 2022 stereo remaster of the original mix. After the release, On my Apple TV, those tracks now playback the new ATMOS version of the main album. If my first sentence above is accurate, one would assume that the stereo mix IS the new one?