Update [Fri 3rd Feb, 2023 01:35 GMT]: A Microsoft spokesperson says the Xbox 360 Marketplace will not be closing in May 2023. The message on the website was apparently "posted in error". Here's the full response (via Gematsu):
"This message was posted in error and we can confirm the Xbox 360 marketplace will not close in May 2023. As a reminder, beginning on February 7, 2023, a limited set of games, add-ons, and in-game content will no longer be purchasable in select markets via the Xbox 360 Store."
Original story [Fri 3rd Feb, 2023 00:35 GMT]: The Xbox website is officially stating as of today that the Xbox 360 Marketplace will be closing "over the next year", with players encouraged to buy any games and DLC off the old marketplace by May of 2023.
You can find this message specifically on the US version of the Xbox Support page. Here's what it says:
"We will be closing the Xbox 360 Marketplace over the next year, so we encourage you to purchase any 360 games or DLC by May 2023."
At the time of writing, we don't have any other details to share about this, and the message doesn't actually appear if you access the Xbox Support website in the UK. If you click the link to the US version, it takes you to a page explaining that various Xbox 360 games are being delisted in February - which had already been revealed earlier this week.
There's a chance this could be a mistake, then, but the wording seems pretty definitive. If you're wondering, it seems unlikely that any of the Xbox 360 games on the modern Xbox Store for Xbox One, Series X and Series S will be affected.
We'll keep you up to date if we get any more official updates about this from Microsoft over the next few hours or days.