Nintendo’s statement reads, “There is no design issue with the Joy-Con controllers, and no widespread proactive repair or replacement effort is underway. A manufacturing variation has resulted in wireless interference with a small number of the left Joy-Con. Moving forward this will not be an issue, as the manufacturing variation has been addressed and corrected at the factory level. We have determined a simple fix can be made to any affected Joy-Con to improve connectivity.”
While the company did not specify what “simple fix” this might be, a report from CNET the other day revealed that a small conductive piece of foam could be the answer. They also reported that newer versions of the Joy-Cons appear to have addressed this issue as well, which is pretty much in line with what Nintendo has said.
In any case if you have yet to buy a Nintendo Switch console, there’s a good chance that the model you purchase would have already addressed this issue, but for those who are experiencing problems, perhaps doing what CNET did by sending it back to Nintendo should fix it as well.