Here is a comprehensive look at what the 1.3.0 update actually offers, why you should stick to official channels, and how to safely manage your game data. What’s New in Pokémon Shining Pearl Version 1.3.0?
Players with a Pokémon Legends: Arceus save file on their Switch (and all main missions completed) can obtain the Azure Flute in their room in Twinleaf Town. This allows a face-to-face encounter with Arceus at the Spear Pillar [2].
The safest and most effective way to get version 1.3.0 is through the official Nintendo servers.
Files labeled as "upd" or "rar" on file-sharing sites are prime targets for malware, keyloggers, and trojans. A file that looks like a game update could easily compromise your PC or console [5].
Nintendo has a robust system for detecting modified software. If you go online with a game patched via an unofficial NSP file, you risk a permanent ban from Nintendo Switch Online services [4].