In dense colloids and simulated glasses, it has been discovered that plastic particle rearrangements correlate with nonphononic low-frequency vibrational modes. Here, we demonstrate that this correlation also holds for a very different material class of complex plasmas under shear, characterized by long-range interactions and nonreciprocal forces. We perform experiments with a deformed amorphous quasi-two-dimensional binary complex plasma under optical pressure, which gives rise to a controlled shear rate, and confirm our findings with extensive particle-resolved computer simulations.