iPhone Bluetooth volume control changed in car

Problems with iPhone and Car Bluetooth Music Volume

I have an iPhone 15P with latest IOS 26.2.1. I drive a 2021 Lexus. Up until recently, when

my phone connected to my car via Bluetooth (not CarPlay), when I played music

from my phone via Bluetooth to the car, all volume control

was through the car audio knob - adjusting the phone’s volume slider did nothing. Reminds me

of the old pre-amp level. This worked great. Lately, however, while the car volume can

still be adjusted with the car radio knob, the volume slider on the phone also

adjusts it and if the phone slider volume is low, the car volume range is too

soft. If I turn the iPhone volume slider up all the way, it works fine but later when disconnected from the car, if I haven't turned it down it startles me. In the Lexus Bluetooth settings on my phone, car stereo is

selected. There are no other setting for input level on the car side. On iPhone side, I've gone through all the sound settings and nothing applies. Did IOS change something? What’s different?