The PS4’s boot ROM verifies the firmware signature and version. Downgrading would require forging Sony’s private key – currently impossible.

To move from 10.50 back to 9.00, enthusiasts use a method known as "Syscon Revert." Every PS4 has two firmware slots: the active one and the previous one (backup). 1. The "Previous Version" Luck

That process takes 4+ hours and has a 70% brick rate.

History shows that the PS4 scene is slow. The 9.00 exploit took over a year to release after 9.00 launched. The developers (TheFlow, SpecterDev) are still working, but they may be saving exploits for the PS5 or a higher firmware. You could wait 1–2 years for a potential 10.50 exploit.

It’s important to clarify upfront: . Sony’s firmware updates are designed to prevent rollbacks, and once the system’s efuses are blown (a one-time hardware change) during an update, lower firmware versions become incompatible.