Spectral evolution of the QPEs in Ansky for the bursts observed by NICER in 2025. The color scheme indicates the time relative to peak (dark at early times, and light at late times). The QPEs undergo hysteresis in the L − kT plane (left panel), which, for a blackbody-like spectrum, can be interpreted as an expanding emission region R_bb (right panel). The error bars represent ±1σ uncertainties.