I am on macOS Sequoia, and audio runs through a multi-channel audio interface. Microphone input is on channel 1 at 44.1Khz; output is to main 1-2.
Since the changeover to WebRTC voice, I have been unable to hear voice from any other users. Others report they can hear me clearly, and when they speak the green "signal" indicators appear above their heads, but I hear no audio. I have confirmed my voice input/output settings are correct (and unchanged since Vivox). I can hear other sounds from Second Life (inworld audio played from inventory, played from script, media streams, etc.) as normal. As of 10-Jun I hear no "echo" in Voice Echo Canyon. Again, I can hear non-voice sounds just fine.
I'm happy to provide any additional information that would be helpful.