To all those who played Borderlands 3 on Stadia, your Vault Hunter's adventures can continue on Steam or Epic after Stadia is discontinued! Google's Stadia platform is shutting down on January 18, 2023, but you can recover your Stadia save file for use on PC on Steam or Epic with this new Borderlands 3 Stadia Save Utility program (a Save Port-o-matic, if you will).
You can find the instructions on how to do it here: https://borderlands.com/en-US/news/2022-12-15-stadia-save-transfer-borderlands-3/
You must complete these steps before January 18, 2023! Once Stadia is no longer active, saves will not be able to be recovered in any way.