Why is the brightness jumping up and down constantly?

1.Which seller did you purchase the product(s) from?
UCTRONICS
2.The Model number of the product(s) you have purchased?
B0266
3.Which Platform are you using the product(s) on?
Raspberry PI 4B
4.Which instruction are you following?
https://www.arducam.com/docs/cameras-for-raspberry-pi/synchronized-stereo-camera-hat/camarry-1mp2-stereoscopic-camera-hat/
5.Has your product ever worked properly?
no
6.What problems are you experiencing?
So after a while I was finally able to get the camera working on my RPi 4. It detects the video0 device, all is good. But then I try to simply capture the video with VLC (or any other software) and I see that the brightness is constantly jumping up several times then back to the original setting. Is there any way to control that?

Also, for some reason I’m unable to control frame rate using v4l2-ctl. The command v4l2-ctl -l only lists exposure, gain and trigger_mode (what is it and what are the values?)

 
7.What attempts at troubleshooting have you already made?

8.How would you like us to help you?