You might want to recalibrate your IMU on the drone.
Usually stitching is better with higher latitudes and overlaps.
As the growing season progresses, the canopy fills in and everything begins to look very homogeneous (all the same). Also the taller crops blow more in the wind making alignment more difficult. This makes it necessary to fly higher so more shared reference features are in each image to align and stitch with. We would suggest flying at 375 - 400 feet (100 - 120m) with 80/80 overlaps over most crops to assist in better stitching.