Looking into thermals and looking at the junction to mounting base, one would expect a package with a bigger cross sectional area on the PCB to have a lower thermal resistance. However, the LFPAK88 package has lower R_th(j-mb) than the D²PAK types, due to the thickness within the package. The drain tab with the LFPAK88 is much thinner, meaning the heat has less distance to travel.