stlread returns different numbers of vertices/points

I'm using MATLAB R2019b. I have to edit a .m file which uses an accompanied stlread(). This one returns a struct stl, and I can use stl.vertices to get the points of the model.

From R2018b onwards, the stlread() and stlwrite() seem to be completely rewritten, returning a triangulation stl. The points are accessed through stl.Points. However, the number of points (as well as the loading time) drastically reduce. This new stlread() loads my sample file 5 times faster, and produces 10 times smaller number of points.

What really changed in the new stlread()? Can I directly modify stl.Points (e.g. rotate the point cloud,...)?