Latest update and iPhone Microphone continuously connecting to the iMac. How do I stop it?

Since my iMac and iPhone have updated, my iPhone continuously tries to connect to the iMac through the microphone when I have any programme running on the iMac which uses it’s own microphone.

I have tried both “Pause” and “Disconnect”, which are the two options on the iPhone when it continuously pings me to say that it’s connected, but with absolutely no effect. I have had a look in both the iMac and iPhone settings, but there seems to be no mention of how to permanently disconnect the two.