  Kagome metals AV3Sb5 (A = K, Cs, Rb) provide a rich platform for intertwined
orders, where evidence for time-reversal symmetry breaking, likely due to the
long-sought loop currents, has emerged in STM and muon spin relaxation
experiments. An isotropic component in the spontaneous optical rotation has
also been reported, and it was interpreted as the magneto-optic Kerr effect
arising from time-reversal symmetry breaking. Intriguingly, the observed
rotations differ by five orders of magnitude between different wavelengths and
samples, suggesting more intricate physics. Here we report optical rotation and
polar Kerr measurements in CsV3Sb5 crystals at the same wavelength. We observe
large isotropic components of 1 milliradian in the optical rotation that do not
respond to applied magnetic fields but flip sign between samples, while the
spontaneous Kerr signal is less than 20 nanoradian. Our results prove
unambiguously that the reported isotropic rotation is not related to
time-reversal symmetry breaking but instead indicates a new intertwined order
that onsets at the same temperature.
