Lightning adapter convert to 3.5 mm jack echo issue while calling

On my iPhone 12 pro max people who call me hear an echo when I use a lightning adapter coverter to 3.5 mm jack. There is no echo if I use the speaker phone or talk on the phone. I got a new Plantronics headset as I thought that was the problem. This did not resolve it. Just updated iOS to 15. No help either.

How do I resolve the issue? Thanks for your help