Radio flux densities as a function of the observed (bottom x-axis) and rest-frame (top x-axis) frequency of MQC J021+19 (left), MQC J133−02 (central), and PSO J200−13 (right). The corresponding radio surveys are shown in the legend. Due to the potential flux density variability of MQC 021+19, we report the spectral fit of the two values closest in time (RACS_mid and VLASS 2.2). Similarly for PSO J200−13, which shows clear evidence of variability on timescales of years. We report the single power-law fit computed between WALLABY December 2021 and VLASS 2.2, which are the two values closest in time.