I started using pi-hole recently. When going over my DNS logs, I found some apps that I explicitly restricted the permission to run in the background are able to start themselves up and make network requests to their hearts content soon after device powers on, and you unlock the screen.
Most of the apps people use doesn't need to start up at the boot. If that app has internet permission, it causes a privacy leak. Even if you use FOSS apps, say one of those AniList clients that are available on f-droid they make request to AniList API every time you reboot your device even if you set battery permission to restricted for that app. Even though I use that app once or twice a week, because of the startup permission of the app AniList conveniently receives my IP address every single day.
Sure you could turn on airplane mode before rebooting your device, or toggle internet permission off but even then the apps will start and attempt network connection, which presumably slows down boot time. Can we take care of the root problem - I say startup permission should be toggleable for individual apps like we can toggle internet and sensors permissions. In the meantime, I am curious if I can take away startup permission from specific apps using ADB and whether the permission will retain throughout updates.