I have the firmware, but it will not help you, you cannot downgrade the firmware from high to low. only firmware via UART will help you, information is in the topic.
The picture at night is good on this camera. It's hard for a phone to increase 12 mp in hik-connect :) better take a closer look at the AN-I91DB0102 camera, it has a good price now
you flashed the camera with third-party firmware, do you think that they will provide you with support in restoring it?
If you don't understand firmware, it's better not to do this.