Private space station launch provider Vast has experienced significant delays, prompting a change in its materials selection. Instead of using stainless steel, which was initially chosen for its durability, Vast will now utilize an alternative material. The exact reasons behind this shift and the revised timeline remain undisclosed.
Source: https://aviationweek.com/space/space-exploration/vast-delays-private-space-station-launch-ditches-stainless-steel