Hi I'm wondering if you can advise me what to do about my front wheels.

I've used wonder wheels/hot wheels, and also plentyl coats of Valet Pro Mulberry wheel cleaner, agitated, power washed, everything really.

This brown stuff just won't shift, and it's definitely sitting on top of the paint as I can scape it off with a flat screwdriver. (The wheels have had a coat of Gyeon on them in the past)

It might be debris from my racing pads or perhaps from the discs; but i'm not sure. It's only on the front side of the spokes.

Any ideas?