"android.uid.system means this app runs with system-level privileges, the same as core Android services. This only works if the APK is signed with the manufacturer's platform certificate."
These apk's are signed with android default platform key. This private key is available in android repos, so it's possible to patch apk and debloat it.
These apk's are signed with android default platform key. This private key is available in android repos, so it's possible to patch apk and debloat it.