Splatoon underwent a little maintenance earlier tonight. That was likely to pave the way for a new update, as version 2.12.0 is out now.
Unsurprisingly, the update doesn’t introduce any new features or additions. It’s instead intended to address a couple of specific issues.
Nintendo’s official patch notes are as follows:
Multiplayer Bug Fixes
Fixed an issue which mistakenly allowed Sprinklers to be placed inside the Tower in Tower Control.
Kelp Dome: Fixed an issue in all game modes that allowed players to move inside the raised starting platforms.