When driving at 100kmph the brake warning light turns on?

This light will come on if the parking brake is pulled lightly or the brake fluid sensor inside the brake master is bad, to check for sure you can ground out the level sensor which is the ORG wire. If this doesn't work, it could be the instrument cluster itself is going bad. Also, I would check the parking brake handle position. I would do a CAN scan to see if nay codes are stored. You can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Thanks for the image, it helps. Please let us know what happens.