I always try turning off the internal supports (checkbox) and see if they are even needed. Often you can get away with either no internal supports or just a few internal supports,
This. being smart with orientation and a bit bold with the red (support needed) warnings can go a long way toward avoiding internal supports, especially on parts like these.
I have been experimenting with lattices recently and have encountered cases where PreForm would light up a model in red despite it being self-supported… it seems that the fine lattice (composed of short rods a bit less than 1mm in Ø) wasn’t considered as sufficient to support the rest of the geometry. Parts still printed fine and are very rigid even on the Z axis so the warning wasn’t really necessary.