Period change analysis of the XY Leo A system. The panels display successive stages of the O − C analysis. The top panel shows the O − C diagram fitted with two LITE terms and a long-term modulation. The first LITE signal (P ≈ 20 yr) is attributed to the well-established third body, XY Leo B. The second LITE term (second panel, P ≈ 23 yr) is included for completeness; however, magnetic activity is considered a more plausible explanation than an additional stellar component. The third panel presents the final residuals, (O − C)_III, which exhibit a coherent quasi-cyclic modulation. The bottom panel shows the Lomb–Scargle periodogram of the (O − C)_III residuals, revealing a dominant cycle at ﹩{P}_{{(O-C)}_{{\rm{III}}}}=14.2\pm 0.8﹩ yr, consistent with a magnetic activity cycle of Applegate type.