Comparison between rest-frame 1.4 GHz spectral luminosity L_1.4 GHz obtained from 3 GHz stacks (x-axis) and ancillary radio stacks (y-axis) using VLA (1.4 GHz, circles) and MIGHTEE (1.3 GHz, squares) data. We assumed a single spectral index α = −0.75 to scale flux densities from 3 GHz to 1.4 GHz. Colours indicate different M_⋆ ranges. Downward arrows with open symbols mark 3σ upper limits if S/N < 3. The broad agreement between the various datasets suggests that using a single α = −0.75 is a reasonable assumption across the full M_⋆ range explored in this work.