MacBook Bluetooth headset audio drops on input

Bluetooth headset output audio drops out, signalled by chime, every time it detects input audio.

Using bluetooth headset (Sony 1000-XM4) with MacBook Neo (Tahoe 26.5.2). About a week ago, encountered this issue in Zoom calls:

• I speak, a chime sound goes off, and all sound in the my headphones drops out for 30-40 seconds
• Other people in the meeting say they can still hear me
• The chime sounds again and output audio returns

This also happens outside of Zoom. If I'm listening to music through this setup and say something, the chime goes off, I lose all audio for a short period.

I have:

• Unpaired and repaired the headset
• Reset the Mac Bluetooth module
• Tested by switching to internal system mic, system defaults for input and output, aggregate locked input and output
• I have isolated all apps that play audio
• I have turned off all apps' access to the microphone
• I have worked with Zoom support to troubleshoot

Looking for any guidance, thanks!