A "stock" of celery?
All kidding aside, I actually ran into the same problem. I thought I was having the issue with the Roav SmartCharge. I have the Roav Dashcam C1 plugged into it. In my car (Toyota RAV4).... 12V port, it worked great. No issues with disconnection of power nor power staying on even when car was off. But in the hubby's BMW 325i thru the cigarette lighter, the power would remain on ALL THE TIME. Therefore, the Dashcam was on continuous recording and never really switched to Parking Monitor. I also thought this was due to the fact that his was powered thru the cigarette lighter, NOPE! I tried it in my cigarette lighter too, worked fine. So after some investigation, I've concluded that it's the car. I tried several different brands and makes of the USB charger (Belkin, Roav SmartCharge, Anker PowerDrive, etc.) and all was the same in his car...... kept the Dashcam powered on. One thing that was different though, the Belkin actually kept a firm connection ....where the charging indicator on the Dashcam would show that it was plugged in.
I now tease my hubby and tell him that his BMW sucks because he loves his car. Hahaha. So when we use the Dashcam in his car, we always have to unplug it when we exit the car so that Parking Monitor would come on. But in my car, I can keep it plugged in and it doesn't draw any energy from my car battery so the Dashcam does go into Parking Monitor.
Therefore, I don't think it's your plugs fault nor the fact that you betrayed Anker by using another brand (). It's your car.