Measured polarisation properties of FRB 20201020A. The top panel shows the Stokes parameters I (black), Q (blue) and U (yellow) as a function of frequency, calibrated by assuming Stokes V to be zero. The second panel shows the measured phase between Q and U (black dots) and its fit in green. The bottom panel shows the RM-synthesis solution, with the polarised amplitude as a function of RM. The dashed green line marks the position of the maximum, at RM=+110 ± 69 pc cm⁻³. The inset shows the same, but zoomed in at the central peak of the polarised amplitude.