Microphone confusion when Mac Studio is connected to MacBook Pro

I use Mac Studio monitor as my monitor and connect it to MacBook Pro. When I am in a Teams meeting, people complain that there is echo. Then I plug in EarPods and the problems get solved. My guess is that when I am not using EarPods, two microphones are active: one from MacBook and one from Mac Studio. So since two microphones receive voice, it creates an echo. I would have expected that when Max Studio is connected to MacBook, one of the microphones should switch off (logical is that microphone of MacBook is switched off). But apparently Apple did not think about this. So what is the solution? I should add that I use Teams under Parallels. So maybe Parallels does not understand that Mac Studio is connected to MacBook.