Posterior distribution of the IGM parameters of the disfavoured models at z = 9.1 for the Varying A_r scenario. Red refers to the case when each redshift is considered separately (Single-z), while blue represents the joint MCMC analysis obtained at z = 9.1 (Joint-z). The contour levels in the two-dimensional contour plots refer to the 1σ and 2σ credible intervals of the models disfavoured by the LOFAR upper limit from Mertens et al. (2025) at this redshift. The diagonal panels represent the corresponding marginalised probability distributions of each parameter.