XMM-Newton background-subtracted light curve of the two observations of eRO-QPE1, named Obs1 and Obs2 (left and right panels, respectively). The full energy band was used, even though eRO-QPE1 shows little signal above ≳1.5 − 2.0 keV, even in the bright phase (A21). The two observations are separated by roughly a week; the times shown are scaled by the start time of each observation (with modified Julian date t_Obs1, 0 ∼ 59 057.834 and t_Obs2, 0 ∼ 59 065.988). Top panels: total model fitted (green line and 1σ shaded area), which is composed of one (Obs2) or five (Obs1) individual bursts (blue), each with a profile described by Eq. (1). A constant value for the quiescence is also added to the model. The inset in the top left panel shows the peak of the last eruption in Obs1, left out from the linear scale, which was adopted for clearer visualization of the fainter bursts. Bottom panels: ratio of the data to the model, where the shaded contours show the uncertainty in the model.