Thank you very much for uploading the files.
We have investigated your project, and we can confirm that your initial idea was correct; it is the lack of sufficient overlap that is causing the color imbalance in the Orthomosaic.
It seems that the mission planning app used the full resolution camera model to calculate the waypoints for the 80%/60% overlap, even though you were not using the full resolution model, which then caused the images to have less than 80%/60% overlap.
We kindly suggest to use the full resolution of the camera model next time.
Nevertheless, the accuracy of your project should not be affected by this color imbalance in the Orthomosaic.