150 MHz radio power versus cluster mass diagram colour-coded based on the cluster redshift with (right) and without (left) the redshift evolution of the correlation. Circles are from the Planck clusters with relics in LoTSS-DR2 (Jones et al. 2023), without distinction of single, double, or candidate radio relics; squares are the NW and SE relics in the ‘el Gordo’ cluster re-scaled to 150 MHz using the measured spectral indices (i.e. α = −1.4 ± 0.3 and α = −1.3 ± 0.3, respectively; see Kale et al. 2025); the star is the sum of R1 and R2 in PSZ2G091. Best-fit correlations are displayed; from Jones et al. (2023), the BCES orthogonal is shown as a light dashed black line, and the BCES Y|X is shown as a light dot-dashed black line; from this work, which also includes PSZ2G091 and ‘el Gordo’, the BCES orthogonal is shown as a light solid black line, and the BCES Y|X is shown as solid black tick. Shaded regions represent the 68% confidence area of the correlations.