Prompted by the rise in sites that purport to offer Steam Decks for a discount, Valve has cautioned against the use of unofficial retailers.
Seeing as Valve quite frequently lurk in forums, news sites, and YouTube, I'd say it's impossible Valve missed GamingOnLinux's coverage of this topic.
The site in question–steamdeck (dot) info–participate in shady and outright dangerous behaviors. Activities like selling Steam Accounts and Steam Gifts that require you to add their account as a friend. These two activities are expressly forbidden in Steam's Subscriber Agreement and will result in your account getting permanently banned.
But this site (not mentioned by name in Valve's warning mind you) is also "selling" Steam Decks at a discount.
At first blush, this site is obviously shady and unofficial and it's a good thing Valve's come out against them.
As they mentioned, there are only two official authorized Steam Deck retailers: Steam for the US, Canada, EU, and UK, and Komodo for Japan, South Korea, Taiwan, and Hong Kong.
No matter what, though, these unofficial retailers–if they actually even deliver on purchases made through their site–do not provide warranties or additional service and can be quite dangerous. If you're going to buy a Deck, do so through official channels.
I would suggest that Valve roll out the Deck in as many regions as possible to prevent this kind of grey market from cropping up and to protect their potential customers, but seeing as this site only ships to the US and UK, it makes that point kinda moot.