LS periodograms of the LOFAR cross-epoch radio light curve, which includes data from both the original LoTSS DR2 epoch and our ten LOFAR follow-up epochs. The spectrum reveals the peak at f₁ ≈ 0.325 h⁻¹ originally discovered by Vedantham et al. (2023). Another significant peak not previously discovered is detected at f₂ ≈ 1.271 h⁻¹, with a false alarm probability (FAP) of less than 0.3%. The locations of these two peaks are indicated by the black arrows. The three dashed red lines represent the FAP of different values. The grey curve represents the LS periodogram of the window function, which is a light curve with the same timestamps as the original curve; however, the flux density of each data point is replaced by unity (i.e. a flat light curve). The inset plot in each panel shows a zoomed-in version of the observed J1019+65 power spectrum in the vicinity of the tallest LS peak, with the same three FAP dashed red lines.