Centrality dependence of $\gamma_{\alpha\beta}(\Psi_{\text{PP}})/ v_2(\Psi_{\text{PP}})$ (black) and $\gamma_{\alpha\beta}(\Psi_{\text{SP}})/v_2(\Psi_{\text{SP}})$ (red), where pairs of particles in $\gamma_{\alpha\beta}$ are either of the same charge or the opposite charge in Pb--Pb collisions at $\snn = 5.02$ TeV. Filled markers correspond to OS correlations, open markers to SS correlations, with vertical bars representing statistical uncertainties and boxes representing systematic uncertainties.