https://wccftech.com/animal-crossing-new-horizons-update-1-4-0-island-backup-dreaming-fireworks/

Animal Crossing New Horizons update 1.4.0 has been rolled out by Nintendo and we’ve got you covered with the release notes.

As covered earlier this week, the brand-new patch is part of the game’s Summer Update, and allows players to backup and restore their Islands through the Island Backup & Restoration Service. To use this service, however, players are required to be a Nintendo Switch Online member.