4 sourced reports, with what to check before you buy. Each one links to the page it was reported on.
Costly or dangerous
Series X system software slows to a crawl and games fail to load until a factory reset
A July 2024 EU-market Series X owner reports the console suddenly slowing down, games stuttering and failing to load with error codes 0x87e5002b / 0x87e50033, delayed inputs and 5-6 minute save loads; only a full factory reset restores it, and the problem recurred ~5 weeks later. The owner notes the same issue is widely reported on Microsoft's forum and Reddit with no identified cause or permanent fix.
What to check. Expect a recurring software-level slowdown that a hard reset does not fix; only a factory reset restores the console, and it can return weeks later. This is a firmware/OS issue, not a hardware fault, so a warranty return may not resolve it.
First-party controller thumbsticks drift within months of use
In a French owner forum thread, a user describes the 'disastrous reliability' of Xbox controllers with stick drift appearing within a few months, alongside controller disconnects and the console failing to power on. This is an owner-reported failure of the bundled controller rather than the console body.
What to check. The bundled controller's thumbsticks are the weak point, drifting within months. Plan for a replacement controller or a Hall-effect third-party unit; the console itself is not the failing part.
Series X shuts down immediately when internal temperature exceeds what the cooling system can handle
A tech outlet covering the Series X reports that unexpected shutdowns are one of the most common problems, and that poor ventilation or blocked vents cause overheating, after which the console shuts down immediately to protect itself.
What to check. Keep 4-6 inches of clearance around the console and clean the vents; a blocked or poorly ventilated unit will shut down mid-game. This is preventable with placement, not a defect requiring repair.
Series X emits coil whine in standby while downloading
A new Series X All Digital owner reports a high-frequency, annoying coil-whine noise in standby mode while a game downloads, stopping when the download finishes. The owner sent the console for repair and the report stated it was 'repaired' and tested, but nothing was actually fixed.
What to check. Coil whine during standby downloads is audible across the room and a warranty repair may not fix it (this owner's unit came back unchanged). It is cosmetic/noise rather than a functional failure, but it is persistent.
These reports come from the pages linked under each item: owner forums, repair guides and workshops. They are not a diagnosis of any one unit, and a careful check of the one you are buying still applies.
Text from the Kriko Gaming consoles catalog, version 0.1.1, under the CC-BY-SA-4.0 license.