https://bugs.freedesktop.org/show_bug.cgi?id=105718
--- Comment #3 from wedens13@yandex.ru --- I have exactly the same issue with Sapphire Pulse Vega 56. It also reports some unreasonably high value (something around 3000rpm) as max fans RPM.
I've found this thread https://www.hwinfo.com/forum/Thread-Solved-SAPPHIRE-PULSE-Radeon%E2%84%A2-RX.... Apparently this issue was solved in windows with AMD driver update.