Instrument panel and brake lights?

First I would check the brake light bulbs, see if one is out and if so replace it, it can have high resistance and cause a voltage drop. Next, there is one item that ties these systems together which is the IPM, integrated power module which is under the hood on the left side. These can go out, to be sure you should do a CAN scan which might have a trouble code to help confirm the issue. Check out the images (below). Please upload an image or a short video in your response, so I can see what's going on.