Corrected dielectron yields as a function of $S/B$ in two different mass intervals, i.e. 0.18-0.5 GeV/$c^2$ (left panel) and 0.5-0.7, GeV/$c^2$ (right panel), for $0.2 p_{\rm T,e} < 10$ GeV/$c$ and $|\eta_{\rm e}|< 0.8$ in the 10% most central Pb$-$Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV. The red curves show the expected dependence assuming a bias of the estimated background of the order of $\pm 10^{-4}$ ($b = -10^{-4}$ in Eq.(5)).