Borderlands 3 is now officially available on Stadia, but without the most recent hot-fixes and updates. The version released is from October, with Google promising that the subsequent hot-fixes and endgame content that is missing will be added in the new year.
The likely reason will be due to Stadia titles being especially compiled for the platform, rather than PC versions running in the cloud. This highlights a potential weakness in the platform, as it means games will have to be maintained seperately much as they would for Xbox or PlayStation, and adds extra development burdon.
2K confirmed in a press release that the Stadia version will only include updates "through to October 24th" and "Noteworthy features coming to Borderlands 3 in early 2020 include endgame content like the Takedown at the Miliwan Blacksite and Mayhem 4 difficulty" among other content. As such, currently the Stadia version is behind it's console and PC counterparts.
Does this mean that the Stadia version will always be several months behind? This makes the platform a less promising prospect in my eyes. It also means the first expansion, due to release very soon, won't be on Stadia's version for the next few months either.
2K haven't confirmed what the update situation will be once Stadia catches up, but we'll be sure to bring you any further news on that as we learn it.