Considering it is Apple they could also be using a proprietary profile that side-steps this issue, especially since they created their own Bluetooth chip (Apple Hx). But again, I don't know if this is true or not since I don't have an iPhone to test.
The second-generation Airpods Pro even do feature a custom low-latency audio codec, but it's apparently only used for the Vision Pro (which is a real shame, as it would be extremely useful for latency-critical things like playing rhythm games on iOS and macOS as well).
On the standards side, there's Bluetooth LE audio, which also offers very low latency, but that might actually require hardware changes (I believe there's reliance on some hardware layer changes).
