Funny you should say that because one of the issues with Catalina was MacOS forcing all headsets, airpods included, to use the terrible default codec I was explaining. Moreover, this then forces all other audio data on the system down to the same terrible quality [1]. The official response was that this was "expected behavior".
This is probably also the explanation for annoyance #3 in the article.
[1] https://apple.stackexchange.com/questions/282705/airpods-ext...