Meet.jit.si: Audio failure on Mac OS Mohave Version 10.14.6 with Safari

On 20 Sep 2020 in a meet.jit.si conference a user on a Mac OS Mohave Version
10.14.6 with Safari had good video, we could all hear him, but he could not hear us.

He then tried firefox and was unable to connect. He reported a grey screen, but it wasn’t clear.

He switched to a Dell PC with Chrome and the conference worked great.