As of the Castles/Precursor update on Xbox, you are up to date with the newest version of Subnautica. However, the PC version is getting a new update within the next week or so.
You should always expect console versions to be ~1 update behind the rest.
According to the trello Xbox might be getting that update at the same time. Even if this one doesn't launch at the same time the next one probably will. Precursor took a while because it also had a lot of the optimization for Xbox, but the C&C update was on Xbox the same month PC got it.
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You should always expect console versions to be ~1 update behind the rest.