Time series, periodograms, and Gaussian process (GP) regression fits for the activity indicators B_ℓ (upper panel) and dTemp (lower panel). Each panel is divided into four subpanels. The upper-left subpanel shows the time series of this indicator (black dots), along with its GP fit (colored lines). The same, focused on the 2023 observations, are shown in the lower-right subpanel. The residuals of these fits are in the bottom subpanel. The upper-right subpanel displays the Lomb-Scargle periodogram of the activity indicator. In these subpanels, the vertical dashed blue line marks the known rotation periods of GJ 4274 (P_rot = 4.59 d). The horizontal black lines (solid, dashed, and dotted) indicate false alarm probabilities (FAPs) of 10%, 1%, and 0.1%, respectively.