Data usage setting not functioning

I have a moto e6 running android 9. I have tinkered, trying to minimize unwanted background data usage and memory utilization. Now the data usage, visible via settings, doesn’t work, staying at 0. What have I done? Or, what controls this?

I use NetGuard firewall. I preferred NoRoot, but it evidently doesn’t forward IPv6.

Android 9 is too bloated for this device, and a lot of the settings have become nonsense since android 7, my previous android.