Apple TV Remote app not controlling volume after update?
Just a heads up to any searching for this. If you’re iPhone volume buttons just recently stopped controlling your TV/Soundbar CEC/ARC setup, go to settings>remotes & devices>Remote App & Devices>then hold your phone near your Apple TV while on this screen to re-pair it to the Apple TV. Once you see it listed on the screen full volume button control will work again with your iPhone side buttons.
Hope this helps anyone else going crazy like I was!
iPhone 13 Mini