It
It definitely is a bit wonky. Sometimes it takes a flip or 2 to move out of PA back to CB.I copy. Now THAT is a problem.
Typically when you switch from Cb to PA all of the transmit voltages are disabled... so NO carrier should be generated.
I wonder if the CB/PA switch itself is flaky. As in.... you switch it to PA....BUT it leaves the RF circuits powered up? THAT could answer for BOTH the CB audio over the PA speaker AND the transmit a carrier when keyed in PA issue.