When you rejoin the webinar as a panelist after encountering a crash, you can’t use computer audio. You will also see the error message "Your audio was disconnected to avoid echo."
When you rejoin after the RingCentral app crashes, your audio state is still on from the server. although he might didn't connect the audio this time, that error state would only last several seconds, then will recover, and work correctly.
Wait for a few seconds before reconnecting your audio. If the error occurs, rejoin the webinar again after a few seconds. Alternatively, you can join the webinar from a different browser, the RingCentral desktop app, or RingCentral mobile app.