At some point they need to demonstrate a ship reentry that doesn’t burn pieces off the flaps. This has not happened yet.
It’s almost impossible unless they can find a material that can go from 5 kelvin to 5000 kelvin to 280 kelvin over a few minutes with no structural stress
true, but the flaps do not have complete tiles on them, remember this is still a development program, starship V# is coming up soon. 1 more launch of the block 2 starship flight 11