When Hal Jordan debuted in 1959, the Guardians of the Universe declared an absolute vulnerability: power rings could not affect anything yellow. In 1994 and later in Geoff Johns' Green Lantern: Rebirth (2004), this was explained as Parallax—the primordial living embodiment of Fear—trapped within the Central Power Battery on Oa. Its yellow wavelength tainted the emerald energy pool, making green willpower completely inert against pure yellow objects unless a Lantern acknowledged and mastered overwhelming fear.
HBO's modern serialized adaptation replaces the literal "yellow paint destroys a force field" trope with an emotional electromagnetic physics model. Fear isn't magic paint; it's an entropic harmonic frequency (589nm resonance) that destabilizes the crystalline quantum lattice of willpower constructs. Rather than an arbitrary color blindness, green constructs can withstand yellow energy if the ring-wielder dynamically modulates their willpower frequency with exact anti-phase harmonics.