This is rarely mentioned. Because of its design, Starship can't just go to the Moon, it first requires orbital refueling (from other Starships). NASA estimates they would need at least 15, but that was before the Starship payload capacity was downgraded.
A couple of engines in the lower stage always fail, but with only a small dummy load that isn't a problem for the test flight. Something in the upper stage exploded, probably a ruptured fuel line.
Ahhh so we are basically at the "everyone left at Space-X that isn't totally burnt out are failson Elon Musk fankids and cultists and his company has lost institutional capability and can't build rockets anymore"?
I think the initial idea is so bad that engineers have a hard problem working around that. Stainless steel should make it easier to use in cold & hot situations, so they can save weight on the heat shield (and it is already very heavy), but now they have rupturing fuel lines and engines.