This is because it appears that even when a call has ended, the app still seems to be accessing their computer’s microphone, potentially listening to the user even though the meeting has ended. The only way to fix this would be to quit the app entirely.
This was initially reported back in 2021 and Zoom pushed out an update towards the end of the year that was supposed to have addressed the problem, but users still reported that it persisted. There was another update last month which did fix the issue for some users, but some users on macOS Monterey are claiming that it’s still a problem for them.
We’re not sure if this is specific to macOS Monterey or if the bug in the app is universal across the various macOS versions, but we can imagine it is quite disconcerting. Until this matter is fully resolved, if you still see the microphone or camera indicator on even after the call has ended and you’ve hung up, the best thing to do is just quit the app.