Nonthermal pressure fraction profile of the Perseus cluster, compared with A2029 (grey points; XRISM Collaboration 2025b). Colors follow the same scheme as in Fig. 4 for Perseus. The shaded bands show numerical predictions from TNG cosmological simulations for two cluster subsamples: (i) the 31 most relaxed clusters from the TNG-300 simulation suite (yellow) and (ii) 30 Perseus-like massive, cool-core clusters from TNG-Cluster suite (pink). The bands represent the 10th-90th percentile range of the f_nth distribution within each sample. The inner AGN-dominant region, as well as the regions overlapping the eastern X-ray surface brightness excess (E+NE and O3), show high f_nth (> 7%; see Sect. 4.1).