Free Play Days have returned to the Borderlands. From 9 AM PT on Thursday April 8 to 9 AM PT on Monday April 12, play Borderlands 3 free with your Stadia Pro subscription.
Vault Hunters… assemble your friends and prepare for all the four-player mischief, mayhem, and madness you can muster. Not yet a Stadia Pro member? Try it free
for a month right now.
Credit also to the OP at MyDealz for spotting this earlier
Hope it helps someone.