Hmm. I stream all my music. There is definitely stuff that is just upmixed, the old stuff run through a processor so they can slap an Atmos tag on it. Then there is stuff that has been remastered using AI to separate out tracks and then remixed (like the Beatles catalogue), and new stuff that is mixed in Atmos with stereo versions released also. You can usually tell fairly easily.
The mixed in Atmos stuff is usually clearly defined positionally, where as upmixed stuff tends to be washed out a bit.