In the MacOS version of GTM, the webcam button appears directly beneath the mute button, which increases the chances of accidentally turning on and sharing one's webcam. Which is exactly what happened to me this morning during a meeting, showing everyone a glorious view of me in a bathrobe with bedhead. I'm sure everyone had a good laugh while, with barely subdued panic, I frantically searched for the Stop sharing button.
A simple way to prevent inadvertent cam or screen sharing would be to add a dialog to check, "Are you sure you want to share?" I'm frankly shocked GTM doesn't do this already.