The "Start in F2" option is missing entriely in the F1 2026 driver career mode, forcing you to start with low stats, while the option still exists in the 2025 driver career mode.
Ideas
The 2026 F2 season hasn't been added to the game yet. Based on previous years it will most likely release sometime in late August/ early September.
The 2025 "Start in F2" carreer mode uses the 2024 F2 cars too, so I don't think they need to add any new cars or grid updates and can instead link the 2025 F2 cars (which exist for a while now) to the 2026 driver carreer mode
I'm not sure if there is a better technical term to describe this but it has to do with how they divided the game into different "branches". When the game creates a save file it's either for the old stuff or the new stuff.