Nintendo released the Splatoon 3 version 1.2.1 update for Nintendo Switch with major Rainmaker bug fixes for online play.
Patch notes for the Splatoon 3 version 1.2.1 update are available below via Nintendo:
Fixes to Multiplayer
Fixed an issue in Rainmaker that caused the player who placed the Rainmaker on a checkpoint to appear motionless to other players.
Fixed an issue in Rainmaker where the goal distance count would go to 1 even when the Rainmaker had not reached the goal.
Fixed an issue where, if you got on an inkrail while using the Inkjet or Zipcaster, allies Super Jumping towards you would land at the start point of the inkrail instead of the intended location.