According to solid-state physics and relativistic mechanics, an electron's effective mass or relativistic mass changes depending on its momentum, energy state, and surrounding band structure.
The claim states that the mass of an electron changes with its energy state. In physics, particularly in condensed matter physics (via effective mass in varying band structures) and relativity (via relativistic mass/gamma factor), an electron's dynamical mass depends on its energy state and momentum. The provided papers (e.g., [0], [1], [3], [5]) explicitly discuss how electron effective mass or relativistic mass varies with energy levels, band gaps, and velocity states. Therefore, the claim is supported.