From the evening of 8/31, Starfish Mainstage will be closed due to repair work. During construction, this stage will not be available in Regular, Ranked, and League Battle. The stage will still be playable in Private Battle though. Your understanding is appreciated.
— Squid Research Lab
Source: Splatoon’s Tumblr.
…Wanna play? Buy a Switch.
And if you’ve already got yours, click on Splatoon 2 for everything you need to know about the game. 😀