Comparison between observed HST transmission spectrum of V1298 Tau b (upper panel) and V1298 Tau c (lower panel) with haze grid models of different haze formation efficiency and planet mass. Upper panel: Solid lines represent models assuming 23 M_⊕. Dashed lines represent models with 8 Mθ, which have been rescaled from the 10 M_⊕ haze grid model of planet b. Blue and green represent haze formation efficiencies of 0.01% and 0.001%, respectively. Lower panel: Solid lines represent models assuming 17 M_⊕ rescaled from the 20 Mθ haze grid model for planet c. Dashed lines represent models with 10 Mθ. Blue and green represent haze formation efficiencies of 1% and 0.001%, respectively.