Just because people say it's "taking up their bandwidth" doesn't mean that's what's actually happening.

It might be causing some other kind of issues but a microphone can't really "take up someone's bandwidth"... That's not really how things work.

I have a fancy microphone, but when I’m away from home in a low bandwidth situation I often phone in audio to zoom because it lags less. Lagging video and non-lagging audio seems to bother people less than both lagging.