Average X-ray luminosity variation of nearby M (top) and FGK (bottom) dwarfs over the four eROSITA all-sky surveys (eRASS1 to eRASS4). Blue points represent the average luminosity from individual eRASS epochs, with vertical bars indicating the methodological uncertainties. The orange horizontal band shows the average luminosity obtained from the combined eRASS:4 spectra, while the shaded blue area indicates the 68% confidence interval estimated via bootstrap resampling.