Out of nowhere, the Wii U has received its first firmware update in over two years. This brings the Wii U system to Ver. 5.5.5, supposedly adding "improvements to system stability and usability," although there may be more to this update than it seems.
This update was not announced in advance, only being subtly added to Nintendo's support page without fanfare. The Wii U's life officially ended four years ago, on March 3rd, 2017, with the final first party release being the Legend of Zelda: Breath of the Wild. Ever since then, the console has remained mostly dead, besides the occasional eShop-exclusive indie release or stability patch.
Before today, the last firmware update for the console was on September 3rd, 2018. The past four patches for the system all contain the same exact notes, describing "further improvements to overall system stability." This obviously does not go into much detail, but many in the modding community speculate that this is an attempt to remove some system exploits. The Wii U has an active modding scene, especially when it comes to adding cool things to Breath of the Wild, which usually goes against Nintendo's strict brand guidelines. While it can't be known for sure if this is the true reason for this update, it would explain why Nintendo is "supporting" the console in 2021.
Nintendo acknowledging the Wii U is usually a rarity these days, making this update stand out to fans more than usual. Support for the console has completely wound down; the built-in Miiverse service was discontinued three whole years ago, removing actual gameplay functionality from titles such as Xenoblade Chronicles X and Pushmo World. The original Super Mario Maker is removing level-upload support at the end of this month, and the game was delisted from the eShop ahead of this change. It may only be a matter of time until online functionality is removed as well, making titles like Splatoon and the original Mario Kart 8 nearly unplayable.
At the same time, the Wii U was an extremely unsuccessful console, so one can't blame Nintendo for not supporting it much anymore. The Nintendo Switch has sold 80m units in four years, surpassing its predecessor nearly six times over. Despite this, fans are still hoping that no more functionalities are removed from the system. Nintendo is within their legal rights to remove modding-related exploits, but taking anything else away from the console could make some beloved games lost to history entirely. Fortunately, if this patch is any indication, that isn't in the cards just yet.