If you "replace the camera/gimbal You will either:
1, need to send the drone to DJI to do the work.
OR
2. Replace it Yourself....This will involve having to get the new part "Serialized" DJI parts are "matched" to each Drone by a process of...
Do you have any metallic stickers or paint that might be degrading the signal?
The only thing I know from outside of mavic world is an issue where the almanac doesn't update like it should.
You might want to review the RTH information in the manual. RTH behaves differently depending on the distance from the home point. If the drone is close to the home point, it will not climb to the set altitude. Check whether you have RTH set to...
Good positional data aren't just dependent on the number of locked satellites... in the logs you also find something that DJI calls GPSLevel (or Navhealth), it's a kind of confidence computation that tells the flight controller if it can trust...