By the way: I semi-randomly landed again on the dontkillmyapp site, and it notes that killing background apps works differently on different phones—presumably first of all between various manufacturers, since they tend to modify Android somewhat deeply: https://dontkillmyapp.com/google

More to the point, the site reminded me that you might want to verify if Blokada is exempted from ‘battery optimizations’ (works via app info —> ‘Battery’ —> ‘Battery optimization’ for me). I checked NetGuard on my phone, and sure enough I have the ‘optimization’ disabled for the app.

(Let me know if you see this comment, or I'm gonna notify you manually.)