less than a month of its last flight, my drone starts to have moisture inside lens. A small circle at the center of the lens (Inside the glass) is being formed upon starting the drone most especially if the drone starts to take off. It subsides when I turn off the drone. My shots we're blurry and unusable.
Your response regarding this matter is highly appreciated.

Hi there, if the temperature varies greatly between the camera inside and ambient environment, the lens might get foggy. Please leave the drone for a while after powering on at the place that you are going to fly in.
If the fog generates in the lens frequently and will not disappear, I suggest sending the drone in for repair. You may contact the local recommended repair center for service https://www.dji.com/service/repair/centers. Thank you.