Pedal fade is most often caused by:

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Pedal fade happens when hydraulic pressure can’t be maintained during repeated braking. Inside the master cylinder, the primary cup seal keeps the high‑pressure chamber separate from the reservoir side. If that seal fails, fluid leaks past as the piston moves, so pressure drops and the pedal travels farther or feels soft as braking continues. This internal leakage directly reduces the system’s ability to generate and hold braking force, which is why it’s the best explanation for pedal fade. Air in the lines causes a spongy pedal and inconsistent pressure, worn pads reduce braking power but don’t inherently cause a progressive fade during a single stop, and fluid leakage externally will lower fluid level and can lead to severe braking loss—yet the characteristic fading of braking under repeated use points to an internal master cylinder seal problem.