MST-adjusted Fermat potential differences Δϕ = Δϕ^modelλ_int(1 − κ_ext) from LENSTRONOMY for the power-law (red) and composite (blue) model families. The internal MST parameter λ_int is estimated by combining the lens models with the measured velocity dispersion and the external convergence estimate. After adjusting for the MST, the power-law and composite model predictions for the Fermat potential differences become consistent with each other within 1σ.