The Switch's battery indicator has been faulty for some since launch. Some users' battery will appear to drop to one per cent rapidly, even though the battery itself works just fine. With the Switch's most recent update Nintendo has offered a fix, but it's a little tedious.
The Switch's battery indicator bug looks really scary, but it's more annoying than anything else. The fix is equally annoying. In the 3.1 update, Nintendo gives detailed instructions on how to reverse the issue. The short version is that you have to charge the battery to 100 per cent and then run it all the way down two to six times. "The battery charge indicator will improve gradually," Nintendo says.
While some users have found other solutions — one as simple as turning the percentage marker off and on again — a lot of people were already cycling their batteries to fix the problem. It's something you should do when you buy new electronics anyway. This solution is so granular that seeing it all written out like this makes it feel like a real pain in the arse. Still, it's nice to see Nintendo acknowledge the problem and offer a solution, annoying as it may be.
Update: Amended the headline to quote more specifically from Nintendo's suggestion. "The battery charge indicator will improve gradually by repeating this process several times," the page says.