The microphone disconnect security feature aims to make it far more difficult for hackers to use malware or a malicious app to eavesdrop on a device’s surroundings.
The feature was first introduced to Macs by way of Apple’s T2 security chip last year. The security chip ensured that the microphone was physically disconnected from the device when the user shuts their MacBook lid.
https://techcrunch.com/2020/04/03/apple-hardware-microphone-...
Having to literally lift the lid and MacOS readjusting the display every time I want to have a meeting was frustrating. It got to the point where I just bought a cheap USB microphone just to be done with it.
I support having a hardware switch for it so that I can have the choice.
I mean, the microphone is under the lid anyway so you are not doing whoever you are talking to any favours by using it in clamshell mode anyway.
Purism laptops do as well, I believe.