Airpods use AAC-ELD for better microphone quality. While the codec is an open standard, activating it with Airpods is proprietary.
And the alternative, newer "Bluetooth high quality recording" I mentioned in sibling comment is not recommended for real-time communication due to increased latency.
So the situation seems to be more complex than I thought. But I stand by my original sentiment: I dislike the prevalence of bad-sounding Airpods in meetings.