  We examine the Universe's transparency to gamma rays within a Lorentz
Invariance Violation (LIV) framework, focusing on photon subluminal quadratic
corrections driven by a high-energy scale. Based on an explicit calculation, we
provide a new expression for the cross section that overcomes the limitations
of previous approaches and refines existing constraints for the LIV scale,
while we introduce a new approximation that may be useful in LIV scenarios
beyond effective field theory. These improvements appear essential for setting
constraints on LIV effects with future observations at ultra-high energies,
where previous approximations may fall short.
