It’s not just Nintendo Switch Sports that got an update tonight. Around the same time the game was updated, Nintendo also launched a new update for Mario Strikers: Battle League. As with Nintendo Switch Sports, this update is the first to follow the big content update that came out in late 2022.
After you update Mario Strikers: Battle League, the game should be on version 1.3.1. As for the patch notes, they don’t say much. All Nintendo says is that they have “fixed the issue where Rainbow colored? Blocks would not appear during Strikers club season matches”.