Left panel: example of the raw-yield distribution as a function of the minimum non-prompt D$^0$-meson BDT score threshold to determine the non-prompt D$^0$-meson fraction in $3 < \pt < 4$ GeV/$c$. Right panel: $v_2^{\rm sig}$ as a function of $f_{\rm non-prompt}$ in $3 < \pt < 4$ GeV/$c$. The blue band represents the 1$\sigma$ confidence interval obtained from the linear fit.