Exceptional points (Eps) are common in metamaterials if one generically considers nonlinearity of eigenvalues that is also quite common in reality. We have considered these kinds of EP topologically and mentioned related skin effects. One of the typical examples is the Kapitza pendulum in mechanics where the instability of the oscillating inverted pendulum is described by the appearance of EP. Look at our paper “Exceptional points and non-Hermitian skin effects under nonlinearity of eigenvalues” by Tsuneya Yoshida, Takuma Isobe, and Yasuhiro Hatsugai, which has been accepted publication in Physical Review B on January 3, 2025. See also arXiv:2407.20895.