from version 9.60 to 9.00 is . While you can easily upgrade firmware, Sony prevents downgrading to protect against exploits.
Downgrading a PS4 from firmware 9.60 to 9.00 is generally not possible how to downgrade ps4 9.60 to 9.00
You can only revert if your previous installed version was 9.00. If you went from 9.03 to 9.60, you cannot go back to 9.00. from version 9
or a Raspberry Pi/Luckfox Pico, a heat gun, and a USB to TTL adapter. The Process a heat gun