The transverse-momentum-integrated yield ratio of $\phi$/$\pi$ (left) [82] and ${\rm f}_1$/$\pi$ (right) measured in inelastic pp collisions at $\sqrt{s} = 13$ TeV. The statistical and systematic uncertainties on the data points are shown as bars and boxes, respectively. The black solid and dotted lines represent the calculations from the $\gamma_{\rm S}$CSM with different strangeness content of $\phi$ and ${\rm f}_1(1285)$ mesons.