They have been testing a new style of heat shield, which is extremely hard to do, as it involves shaping the nose cone so precisely that it cant be off by even a micron anywhere in its dimensions. They could continue with the old style and never have any issues in flight (which is what they currently do for every manned flight), but the old style heat shields require SIGNIFICANT work after each flight, which makes space travel extraordinarilly expensive and not feasible for mass space flights.
Reinventing the wheel comes with a lot of trial and error. I realize that you arent interested in an honest discussion about this (your petty goal is obviously just to shit on Elon), but i figured i would inform you nonetheless.