Evolution of the main spectral parameters from the 2023 NICER and Swift campaign on MAXI J1834–021 with Models 0 and 1A (left) and 1B (right). The top panels show the unabsorbed flux in the 0.5–10 keV range as estimated from spectral fitting for both NICER (purple squares) and Swift-XRT (orange triangles). The evolution of the main best-fit parameters used in the spectral analysis (Sect. 3.3.1) is plotted in the other panels. In the fourth panel, filled and empty squares differentiate observations where the inclusion of the bbodyrad/diskbb component is significant (in chich case kT_seed=kT_bbody or kT_seed=kT_disc) from those where it is not significant.