no outgoing audio (microphone) with iPhone 11 ProMax and Beltone hearing aids

iPhone 11ProMax - iOS v18.3.1

The mic is switching to my hearing aids - and I can't find a place to turn that setting off since the iOS upgrade to v18. Beltone said it isn't a setting or issue with the hearing aids - it's the phone mic switching.

I've tried to re-pair the hearing aids, but the iOS does not have the option to turn off the mic any more.

with previous iOS this was not an issue. But now I have to blast on speakerphone to have conversations because I can't use my hearing aids without also switching the microphone (which does NOT work for calls!)