The correlation between $v_3\{2\}$ and $v_2\{2\}$ using $q_2^\mathrm{V0C}$ selection in Pb--Pb (left) and Xe--Xe (right) collisions. The open black points, connected by a black line for visibility, show the $q_2$-unbiased correlation from central to peripheral collisions. The $q_2$-differential correlations, with the lowest (highest) $v_2\{2\}$ value corresponding to 0–-10\% (90–-100\%) $q_2$, are shown by the full markers and linear fits in each centrality interval. Error bars (boxes) indicate statistical (systematic) uncertainties.