It happened 19-21 august 2021 for lot of owner of 9360 due to some automated BIOS update.
You are not alone ((
Your chances are:
- If you login into corporate MS account - get recovery key from your admin
- If you login into personal MS account - key could be on https://account.microsoft.com/devices/recoverykey
- Downgrade of BIOS to old version could switch off this Bitlocker Recovery Mode
None of it worked for me, btw.