Time evolution of the ratio of external pressure to gravitational pressure for the seven gas-deficient satellites. Both pressures are computed using Equations (1) and (2), and smoothed over a 50 Myr window to reduce fluctuations. The black dashed horizontal lines mark the point at which P_ext = P_grav. The moment of gas removal for each galaxy is marked with the black arrow. For the galaxy with ID = 236, three distinct sources of strong external pressures are illustrated in the top panels through gas column density maps: (A) fly-by interaction with another galaxy, (B) mild ram pressure, and (C) strong ram pressure. In each map, the black dashed circle indicates 2 R_90, gas, where R_90, gas is the radius enclosing 90% of the ISM gas mass within 3 R_eff.