Siri/Maps volume in Settings missing

There used to be a Settings option to control Siri turn-by-turn volume (in my case, using CarPlay). It used to be something like Loud, Normal, and maybe a third option. That seems to be missing in iOS 15; not sure when it disappeared. Currently Siri is much louder than the background music.

Support pointed me at the control on the right side of CarPlay (when you tap the map), but that seems to control how VERBOSE Siri is, not the volume. Per another suggestion, I tried asking Siri to lower the volume, but that affected the music, not Siri's directions.