Infrared luminosity or the corresponding SFR as a function of CO luminosity, or the corresponding molecular gas mass with the CO-to-H₂ conversion factor α_CO = 5 M_⊙ (K km s⁻¹pc²)⁻¹. GRB hosts are marked with full red circles or red arrows with crosses showing the errors. The symbols of other galaxies are indicated in the legend and described in Sect. 2.4. The solid black line is a linear fit to the non-GRB galaxies excluding ULIRGs Eq. (1), whereas the dashed black line represents the fit including ULIRGs Eq. (2). The ∼0.3 dex shift for GRB hosts towards lower M_H2 is not statistically significant (see Sect. 3.1).