Evolution of the S₈₇₀ flux density of massive quiescent galaxies (MQs) selected at z = 2, 3, and 4 is shown in the first, second, and third panel, respectively. At each selected redshift, MQs are divided into four stellar mass bins of width 0.4 dex, starting from a lower limit of log(M_★/M_⊙) = 10.6. The coloured regions and lines represent the 16th, 50th, and 84th percentiles of MQs within each stellar mass bin. Overall, the S₈₇₀ evolution of MQs exhibits a gradual increase with decreasing redshift, reaching a peak before undergoing a rapid decline at later times. Notably, the most massive MQs consistently display the highest S₈₇₀ peak values.