The S-IVB also ongoing to thrust in a very low level by venting gaseous hydrogen, to keep propellants settled of their tanks and prevent gaseous cavities from forming in propellant feed strains. This venting also taken care of Secure pressures as liquid hydrogen boiled off from the fuel tank. https://lorenzocdcda.blogofoto.com/65112630/considerations-to-know-about-ambiq-semiconductor