No, your eyes are absolutely not deceiving you at all. The Wii U may be all but a memory now, but that hasn’t stopped Nintendo from releasing rare and random firmware updates for the console. Tonight is no exception, with a Wii U firmware update releasing within the past hour.
If you still play on a Wii U, and you still want to download updates, doing so will put your Wii U at version 5.5.6 U. The update’s release may be surprising, but the contents of the official patch notes are not. They’re very small, with Nintendo only saying that “further improvements to overall system stability and other minor adjustments have been made to enhance the user experience”.