Hey there.
Windows TaskManager will not show the actual CPU frequency:
Effective clock vs instant (discrete) clock - HWinfo Forum
You should try to check your CPU core voltage(s) and C6 (deep sleep) power states, instead.
If you see your core voltage drop to 0,8 - 1,025 volts on idle, then everything is working fine.
Check your BIOS setting "Global C-State control", which needs to be enabled for power saving.
And while you are checking these values, have a look at your CPU temps while gaming.
If you can stay below 80°C while gaming, it should be all good there as well.
--- [ CPU: Ryzen 7 3800XT | GPU: ASRock RX 5700XT Challenger Pro 8GB | driver: 24.1.1 ]
--- [ MB: MSI B550-A Pro AGESA 1.2.0.7 | RAM: 2x 16GB 3600-CL16 | chipset: 6.01.25.342 ]