Are you playing on a or a digital download ?
If you still have your cartridge on Version 1.0, you cannot transfer your Necrozma or your event-owned Zeraora to Pokémon Scarlet . The update quietly installed the cryptographic key needed for that final transfer wave in March 2023. Without 1.2, your Pokémon are stuck in Alola forever.
If you’re playing on a hacked 3DS with a ROM or modified save file, installing the official 1.2 update may break certain cheats or mods. Back up your save before updating. That said, most major mods (like Supernova Sun) have been updated to work with 1.2.
The main reason for this patch was to fix a game-breaking bug affecting four specific moves during official "Live Competitions". Using these moves could freeze the game mid-match. The issue was serious enough that the Play! Pokémon circuit had to temporarily ban the following moves: