Aside from what a sibling comment mentioned about fuel sloshing from the flip maneuver, Raptor/Starship use autogenous pressurization (i.e. some of the gas prod

Aside from what a sibling comment mentioned about fuel sloshing from the flip maneuver, Raptor/Starship use autogenous pressurization (i.e. some of the gas produced by the engines is tapped off to pressurize the tanks), so there could have been an issue with that, too.