Hey, have the same radio, and the same problem. Though my PTT adapter is a little different. I have tried to re-work the grounds with no luck. I think my next step might be some sort of simple speaker-delay circuit or thermistor.

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https://www.amazon.com/dp/B09HGR4ZPY?psc=1&ref=ppx\_yo2ov\_dt\_b\_product\_details