a permanent notification is one of the few ways that may work to keep an app alive on android.
some users report that this type of notification would make getting messages in background more reliable and there are reports that this type of notification could also be an idea for Delta Chat (eg. here).
in fact, Delta Chat already uses this type of notification to keep the app alive - but we do this only for the time the screen is turned off (at some point, users were annoyed by the permanent notification and this seemed to be a nice hack)
however, maybe things have changed since then and the permanent notifications are more widely used and can be regarded as a hint that “Things are working”, that “Delta is waiting for messages …”.
this disappearing permanent notification would also be a strong hint that the app has been killed by the system without consent.
what do you think? would you a permanent notification still annoy you? or may it be regarded more as a hint that things are “okay”?