There is no legitimate software-only tool called "PS4 Tool Downgrade v1.00" that can downgrade your console's just by downloading and running an app. If you found a link for this specific name, use extreme caution as it is likely malware or a scam .
Find the game's update .json link on sites like ORBISPatches . Set up your PS4's network to use your PC as a . For Firmware Reverts (Expert Only)