As reported previously, after Nintendo released the12.0.3 firmware for Switch, the update was pulled with no explanation. However, Nintendo has now commented on the situation.
Nintendo has stated that those that have already installed the update may experience connectivity issues in some instances, and those that attempt to use a microSDXC card for the first time will be unable to do so.
Nintendo also says it is currently working to solve the issues with version 12.0.3 and should be solving it soon.