Left panels: Representative NICER power spectra at different phases of the outburst, calculated in the 0.5–12 keV band and labeled from a to f. Right panels: NICER HID (top) and HRD (bottom) of the outburst. The hardness ratio was calculated as (6 − 12)/(2 − 3.5) keV, while the total fractional rms was calculated in the 0.5–64 Hz frequency range (and 0.5–12 keV energy range). In both rows, the colored stars mark the position in the diagrams at which the power spectra were obtained. The presence of strong band-limited noise typical of the HS supports the reactivation of compact jets during the short HIMS phase around MJD 58570. The two drops in X-ray rms variability happening after 58576 and after MJD 58582 could be consistent with the launch of the RK2 and RK3 discrete ejecta, respectively.