How are your subwoofers wired? Are you using an aftermarket amp as well? In that case, does the amp power off properly when you turn off the car?

 

They are wired with a low pass converter, yes I’m using an aftermarket amp, also the amp turns on and off when I close the driver and passenger door, car off

 

And will the humming stop once the amp turns off?

 

Yes, if the amp is off, no more humming

 

So this humming only occurs if you have turned the car (and the music) off and stops when you quit and lock the car?
I believe you could change the wiring so that the amp would only turn on and off with the radio (not when you close the doors). Maybe get the remote power from somewhere behind the radio?
And another option would be to remove the low pass converter and get the RCA output cable kit that connects behind the original stereo.

If you have constant humming, which you just won't hear over the music, relocate the RCA wires - running them over hot wires may cause this.

 

If you still have your factory sub plugged in it will pick up interference. I had the same problem on 2015 and 2017. Unplug your factory sub and see if that solves it. Also what are you using for your remote turn on?

 

change to different brand hi-lo converter to see if that helps with humming after system is off.
you can also try to turn the gain adjustment **** on the hi-lo if it has them.

remote wire should not be hooked to a door trigger.
Should run this Remote Amp turn-on wire to cigarette lighter at the least so when car is on accessory mode then the app will work only.

 

Wait, You have your car doors act as a switch for your amp?
That's weird.
You would have the amp constantly turning on and off every time someone open/closes the doors.