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.
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.