As more people get their shiny new Steam Deck, more problems will inevitably appear not just because hardware can never be perfect but as more system updates roll out — there's a bigger chance for problems and recently stick drift became an issue.
Posting on Reddit, a couple of users (#1, #2) showed some pretty bad stick drift, something other console makers have also had to deal with and it can be a really big issue. Particularly problematic on the Nintendo Switch with the Joy-Cons, something I've personally experienced.
Thankfully, it seems in this case it was a software problem and not a hardware defect, as Valve developer Lawrence Yang said on Twitter:
Hi all, a quick note about Steam Deck thumbsticks. The team has looked into the reported issues and it turns out it was a deadzone regression from a recent firmware update. We just shipped a fix to address the bug, so make sure you’re up to date.
Considering how, unlike the normal Switch models, you can't just easily grab a new controller with the Steam Deck as it's all stuck together inside the casing, this would have been quite the problem for new Deck owners. Let's just hope that Valve is already learning lessons on their update rollouts so things like this don't sneak past them.