Until a full downgrade is possible, here is the for 9.03 users who want to play backups.
: If not properly backed up, downgrading can result in data loss. downgrade ps4 903 to 900 fix
A software USB downgrade from 9.03 to 9.00 is impossible on a retail console. Until a full downgrade is possible, here is the for 9
: Depending on the method, you might need specific exploit tools designed for PS4. These are usually developed by the community and can vary based on your console's model and current firmware. Until a full downgrade is possible
Note: This does not downgrade to 9.00, but it restores 80% of 9.00's functionality via a different exploit.
Some claim you can revert by restoring old save files. Saves are encrypted per firmware.