Golf was announced for Nintendo Switch Sports alongside the game during a February 2022 mini-Nintendo Direct. At the time, the plan was to launch Nintendo Switch Sports at the end of April with six games and then deliver the golf update for free this fall. That plan appears to have fallen apart, however, and Nintendo hasn't provided an explanation. The update is still coming, however, and the latest trailer for Nintendo Switch Sports has revealed more of what players can expect from the golf update.
The golf update for Nintendo Switch Sports will now arrive this holiday season, which likely implies a November or December launch.
That is the problem with live service games. All service, but the backend must be busy fixing bugs or networking code at the tail end of their planning.