This image is off your SD card and not via your RC unit or phone/tablet?
The P3 & P4 are not really that good for night time due to noise, hot pixels (usually white), and high ISO, imho. DJI has a DNG Cleaner software on their website that addresses hot pixel DNG noise to some degree, but you may have pushed the envelope with the HDR at night and exceeded the exposure limits.
I would do a simple DNG shot in the daytime first before trying the night shot, and compare it a JPG too. That way you'd establish whether your DNG images are okay rather than jumping into difficult night shots first with HDR.