Not a true downgrade. The dumps of syscon and sflash from lower fw (in my case 6.72) are able to replay the nonce message back to samu.
This is part of snvs which is encrypted so we can't read that part. If we could, downgrading would be possible
Hi Centrino here, I managed to fix my rtc clock.
Because I'm able to revert, I switched to my 8.00 syscon and sflash. Then signed into psn.
Set clock using Internet.
Turned the ps4 off.
Reverted back to 6.72...clock fixed