Headset - B&O Cisco 980 - sound issue

I have a Bang & Olufsen Cisco 980 headset and I use it via BT.

The issue: I play two videos on YT at the same time in Safari and when I stop any of them, the sound will be gone. So, even if one video is still playing after stopping the other one, I will not hear it at all. In this case I need to stop the playing and start it again.

There are more cases when the sound is gone but they are less reproducible. The above is a clean way to reproduce the issue and it occurs 100% (10/10)

Things I have tried:

• The same issue happens in Chrome.
• The same issue happens with other MBP (Intel based, latest macOS) without having installed Webex.
• There is no issue in wired (3,5 jack) case.
• There is no issue with using a JBL headset.

What can be a the problem?

How can I provide more detail for the investigation?

I have started the investigation on Cisco side but they redirectred me here: Cisco - Bang & Olufsen Cisco 980 - sound source issue on MacBook