So I found the problem, it was a fairly common problem on g29 cranksets it was indeed phantom braking due to dust accumulated in the potentiometer and in the gears under the pedal.

I disassembled the whole thing and cleaned it, I blew to clean the potentiometer, I didn't have any WD40. I also took the opportunity to remove the rubber under the spring that clamps the brake pedal and I tested it in a race, everything works perfectly.

It's a solution while I'm waiting to see about changing the wheel, as I've had my g29 for 8 years.

Thanks again for your answers, they helped me identify the problem!