White balance is off, murky picture, oversaturated, and the second picture is just strange. The last one is taken with iPhone.

I used HDR to take these pictures. None of these pictures are photoshopped.

Now the question: Do I have a defective product, or it is common to all Mavic HDR?

And the gimball is also not leveled. How do I fix this problem? I tried calibration a million times but it is still tilted.

Earthwarden Posted at 2017-7-3 19:31
And the gimball is also not leveled. How do I fix this problem? I tried calibration a million times but it is still tilted.

It is impossible to say that there is anything wrong with the photos because of the time of day that you have taken them.
Try resetting the camera and then take some pictures in the middle of the day.
Under gimbal settings in the GO 4 app. there is a setting to adjust the tilt of the gimbal and get the horizon straight again but you need to do the adjustment on a perfectly flat surface.