Z26 Pads cutting off since day 1

I’m facing an issue with my 2nd set of the Z26 which is at high speed braking when i fully hit the brakes and the car is slowed a bit I feel like a cut off on the brakes like it slides for a second not more than 2 seconds or even less during the stop period, “doesn’t continue to stop” and I also can here it coming from the front sides can’t describe the sound but like the pads are fighting to hold on for that 1 second. And also i can feel it through the brake pedal (shaking,lossing) feeling for the same period. It’s not a big issue unless one day I needed that 1 second to save me from a crash.

What I would do for now is remove the pads sandpaper them all sides because I did forgot to remove the side paint before installing them 7K miles back. But any idea or best way to clean the rotors while they’re installed like quick clean i know using sandpaper by hand is pointless on rotors (unless using a machine) any other ideas? I have my rotors resurfaced same time i did change the pads 7k miles ago because I saw that it needed too after 2 changes, and im within normal specs and even there’s still enough thickness for 2-3 more resurfacing (not planning to but in case). Some might say maybe because of the resurfacing (remember i had it even on the 1st setup). If any did notice this also will love to know to feel a bit better because I’m feeling it’s the Z26 itself doing that maybe try different brand like hawk? After all solutions don’t work out

Cheers all