nimajneb parent
My Pixel 3a XL does this with WiFi, I'm convinced it's never actually off. It will auto connect to remembered WiFi networks even when I "turn WiFi off".
Mine don't. Maybe Settings->Location->Wi-Fi and Bluetooth scanning is the setting that does it.
There you can disable whether apps and services are allowed to scan wifi and/or bluetooth even if they are turned off.
Maybe it's PNO
https://source.android.com/devices/tech/connect/wifi-scan
> On devices running Android 9 or lower, when the device is disconnected from Wi-Fi and the screen is off, PNO scans occur at 20 second intervals for the first three scans, then slow down to one scan every 60 seconds for all subsequent scans. PNO scanning stops when a saved network is found or the screen is turned on.