Why many TWS earbuds are capped to 128 kbit/s AAC?

Dear Apple AirPods 4 / Pro 2 / Pro owners,

When you're in a conference call over the net and listen to music simultaneously, do the earbuds output STEREO music?

There's apparently AAC-ELD-Stereo48K+voice and LC3-Stereo48K+voice modes on AirPods Pro, but neither recent iPhones nor macOS could activate it AFAIK.