Complete these steps to download the update:
- Connect the Nintendo Switch console to the internet.
- Return to the HOME Menu and launch the game.
- The update will be downloaded and installed automatically.
- Once the update is installed, the newest version number will be displayed on the title screen.
Official changelog said:Ver. 1.1.2 (Releasing December 1, 2021)
- Fixed some issues that would prevent the game from progressing under certain circumstances.
- Some issues have also been fixed for more pleasant gameplay.
- Sources
Nintendo Support: How to Update Pokémon Brilliant Diamond and Pokémon Shining Pearl
en-americas-support.nintendo.com