[Nextgrid]

It's AD2P vs HSP profiles. One gives you good (well, compressed but decent enough) stereo audio one way, one provides shitty audio but both ways.

I'm surprised as to why Apple couldn't come up with a better protocol that would manage to do both or switch number of channels & quality seamlessly.

[Causality1]

Nobody seems to care, is the thing. Qualcomm is now deprecating APTX-LL in favor of APTX-Adaptive even though it's 50% laggier even under ideal circumstances.