Why does RDR2 flicker and tear when Path Tracing is enabled at night?

Night scenes in RDR2 looked broken with color overflow and tearing, ruining the immersion. I lowered ray tracing to High, which fixed FPS but killed the visual fidelity. I used DDU to clean install the Studio driver and cleared 6.5GB of shader cache via GamePP. RTSS showed frame generation time dropped from 22-35ms to 13-16ms, restoring visual stability.