By default, Android 10 and 11 limits Wi-Fi scanning, which is produces bad Wi-Fi fingerprints. Disable the "Wi-Fi scan throttling" setting from Developer options, see image below. 

On some devices (e.g. some Huawei models) this option is not visible under developer settings. In that case you can run this command in adb:

Note that you first have to enable Developer options on your device. See Android Developer site for guide.