Not a carrier phone. I don't know what specifically it is, Google Play... something. I disabled automatic updates in Play store, so probably something else. I usually just quickly pull down notification shade and click "Cancel".

Even disabling all available restriction settings often doesn't quite work. For clock app I set it to unrestricted and disabled optimization in DuraSpeed, still, it's a dice roll. The chances are lower when charging. (Ulefone Armor 24)
On previous phone Unrestricted setting and locking in recent apps also didn't quite work, but that phone had more issues. I'd often find that everything just randomly crashed overnight. (Poco X3 Pro)

But it also seems per-app. From experience, the most kill-resistant app is Termux (terminal emulator), but only if you disable child process restriction in developer settings. LibreTorrent also survives well, making the 2 only reliable large background download methods LibreTorrent and wget in Termux.

But anyway, my Alcatel 1066G dumb phone was just 10 bucks. A more reliable solution (and it supports animated GIF wallpapers 🙂).