Prevent macOS from Automatically Switching to Bluetooth Mic Input

Whenever I connect my Bluetooth headphones to my MacBook, macOS automatically switches the input to the headphones’ microphone, causing them to enter call mode and resulting in extremely poor audio quality.

I’ve tried manually changing the input source via the Option key and sound menu, but this doesn’t resolve the issue at its core. Is there a way to prevent macOS from defaulting to the Bluetooth mic?

Thanks for any help!