While it could be an actual issue / bug, any time I’ve encountered this is because I’ve inadvertenly had both radios active in the cockpit at once due to an errant cockpit click that enabled monitoring on the second radio.
You can have 1 radio set for transmit / receive and the second to receive only to monitor another channel like ATIS or a UNICOM frequency. This is a pretty common thing.
How to shut it down depends on which plane you’re flying. GA and airliners will have very different radio stacks.