pic: What's weird with this image

[TikiTech]

I agree this is odd.

Does the condition move if you swap the "Y" output on the motor controllers?
As in the motors do the opposite as they are doing now.

Try swapping the y cable to the one used on the other side and note if the condition follows.
Or just swap the "Y" cables on the RoboRio.

Does the condition follow the cable or stays with the motor controllers?

I would make sure when recalibrating not to use a "Y" cable.
And test each motor separately and not on the "Y cable.
If the problem still exists only when on that specific Y cable, its got issues.

This should narrow down the issue to the cable or one motor controller.

Just curious is the voltage output of those motors indeed opposite to each other.

Hope you get this sorted.

Aloha and good luck this season!