I have a V2 cam that, after being plugged in for several days, develops an audio issue.
There is a very loud high pitch wine/tone that is unbearable to listen to.
It is present in live stream and recordings.
The only way to make it stop, it to physically power cycle the cam (unplug replug), but then the sound comes back a few days later.
It is on firmware 4.28.4.41 which is the RTSP version, but the cam made this sound before when i had it on normal firmware.
Example: