Light curve of J0300−08 in terms of the broadband E = 0.3 − 10 keV flux. The dashed black line represents the flux level of F_{0.3 − 10 keV} = 7.6 × 10⁻¹³ erg cm⁻² s⁻¹ expected from its bolometric luminosity, once the k_bol, X − log L_bol relation from Duras et al. (2020) is assumed. The solid red line indicates the flux reference value for X-ray weakness corresponding to Δα_ox ≤ −0.3 (Pu et al. 2020). The 3σ upper limits from the Swift observations of 2011 and 2021 are shown in green and gold, respectively. The flux from the 2018 XMM-Newton observation analysed in this work is marked in blue.