My experience as an operator and photographer tells me that it is a stain on the sensor ("Tablet") of the camera ...
In professional reflex cameras it is relatively easy to access and clean the sensor ...
In a drone, unless you have the "part list" of your model (something almost impossible in the network ... unless you are a SAT .. "legal" technical assistance service) ... unfortunately you will have to go to a Official DJI SAT ..
If it were on the lens, it would be simpler (and you would know it since that spot would be seen in the same place but more affected by the light conditions ... and the reflection in it ..).
Greetings.
In professional reflex cameras it is relatively easy to access and clean the sensor ...
In a drone, unless you have the "part list" of your model (something almost impossible in the network ... unless you are a SAT .. "legal" technical assistance service) ... unfortunately you will have to go to a Official DJI SAT ..
If it were on the lens, it would be simpler (and you would know it since that spot would be seen in the same place but more affected by the light conditions ... and the reflection in it ..).
Greetings.