Starting yesterday (9th November 2022), Google has started to issue refunds. Eligible content includes games, add-ons and subscriptions (except Stadia Pro) purchased through the Stadia store.
Customers awaiting refunds have been advised not to contact customer support, as they will not be able to speed up the process. Google hopes all refunds will have been issued by the time Stadia servers shut down on 18th January 2023.
Refunds will be distributed through the original method of payment. If this is not possible, emails will be sent with instructions on how to claim the funds issued. If customers have deleted their Google accounts, they will need the email, date of last transaction, and transaction amount in order to start the refund process.
Some hardware such as Stadia controllers are also eligible for refunds, but the Stadia system itself is not, and games stores have been advised not to purchase units. Google advised that any issues with refunds that have been issued should be dealt with via customers' bank/credit company and not Google itself.