Update: reinstalled the drivers and without making any changes in Wattman, the zero-RPM feature seems to work UNTIL you make changes based on my sample size of 1.
GPU BIOS update has little risk. Because with an integrated GPU system, original BIOS can easily be installed even if GPU BIOS is damaged. Also your fan problem is probably driver-releated, not about GPU BIOS.
So do AMD support look at these forums? Is there a way to submit a bug report?
Run Radeon Settings software and follow this way:
Preferences > Report Issues Online > Desktop
This is a driver bug. It intercepts fan control for any interference with the wattman.
I sent letters to AMD. But this is not the main problem today.
You can activate manual fan control and reduce the minimum speed to 17%. Below it is impossible. This is the reason.