Ryzen can idle below 1GHz. I don't know if it is still the case but I know CoreTemp and the Windows task manager used to incorrectly report core frequency, and usually displayed the base clock. Other hardware monitors could report the actual clock speeds though. You might also need to check your power plan (again an old problem that I think Microsoft has fixed) and see what the minimum CPU speed is set to.
Maybe your motherboard is also keeping your CPU speed up so check if there are any enhancements enabled?