The does not exist today. Anyone telling you otherwise is either misinformed or trying to scam you. However, absence of evidence is not evidence of absence. The PS4 scene has a history of delivering surprises long after everyone lost hope.

That said, here's a realistic technical write-up on the status:

Since 8.52 can simply be updated to 9.00, there is zero incentive for a developer to waste time stabilizing an exploit for 8.52. It is a "ghost firmware."

PlayStation 4 firmware 8.52 is compatible with the stable PSFree webkit exploit, allowing for jailbreaking without updating the console. While 8.52 is functional, updating to 9.00 via USB is often recommended for higher stability and better homebrew support using the pOOBs4 exploit. For full details on the jailbreak process, visit ConsoleMods Wiki

Here is the truth: Those users are likely using the that was ported back from the 9.00/10.01/11.00 days.

) to block Sony's update servers and redirect you to exploit hosts. Run the Exploit