So I am also using aftershokz and noticed this problem on wednesday may 11th, so it makes sense this was due to a recent update in Windows or Teams.
It is using the mute and unmute function of the headset itself, because in the past with teams, if I muted myself using the buttons on my headset, this was the symptoms of using the built in mute functionality. So to avoid this issue, I always used the mute function within teams, and then there was no issues.
But now it's super distracting hearing the beeping and the mute on mute off voice everytime I need to participate in a meeting.
I much rather roll back to the previous update then deal with this, My only solution is for me to use a different headset that doesn't have it's own built in mute function. So if you guys have different headsets you can use, try them, as other headsets that don't have verbal queues when your muted will work just fine.
But I want to use my aftershokz as it's perfect for being able to talk to people locally and be in a teams meeting at the same time since they don't cover the ears!