https://bugzilla.kernel.org/show_bug.cgi?id=193981
--- Comment #4 from Fabian plusfabi@gmail.com --- Also maybe not related, but according to sapphire, on OS start, the fan will rotate for a short time (short like 0.5s) at a higher speed, to remove some dust.
Maybe the linux-hwmon taked this dust-removal speed as default value and keeps it for the whole runtime?
In Windows it's that way: a short high rotation speed and then slow down to almost?) 0.