Wow this article was not informative and their links are broken.
This is the support article they are referencing: https://www.amazon.com/gp/help/customer/display.html?nodeId=TY9Z4zZ7vgVwLA0b7C
This is the changes
A-la-carte game purchases are no longer available. Previously purchased titles will remain playable through June 10, 2026, after which they will be removed from Luna.
Bring Your Own Library will no longer be supported. Games previously played in this manner will no longer be playable on Luna after June 10, 2026.
Ubisoft+ and Jackbox Games subscriptions sold through Luna are discontinued. New subscriptions are no longer available for purchase, and any active subscriptions purchased from Luna will be cancelled at the end of your next billing cycle.
Third-party game stores (EA, Ubisoft, and GOG) are being removed from the Luna platform.
For the refund
Can I get a refund for games that I had previously purchased?
All purchases of a-la-carte titles through Luna are final, and we do not accept returns, except as expressly stated in the Digital Products Return Policy. However, you can continue to access your purchased titles through your linked third-party platform account. If you have questions about a specific purchase, please contact Amazon Customer Service.
EDIT: Looks like Amazon Games app might not be included with this, but I not 100% unsure.