SYNC 3 MY20 EU F11 Map update

I believe you are referring to this guide → Tutorial: Sync 3.0.20204 with 2022 EU 2.21 (F11) Map Installation
That guide does not involves reformat, so it’s safe on MY20 models.

You stated the unit is an OEM replacement and that you are positive is MY20.
Do you have the output of the interrogator log?.