Okay so maybe you could argue that if you never "swipe kill" the app it should be allowed to have background services executing much like e.g. Slack on macOS. But you can't even do that. Having your ui in the recent tasks list does not exempt you from background restriction.
When an app gets put in the background it gets an event from the OS it's then the devs job to not keep everything loaded in the background but most don't.
Swiping it away instantly kills the app unless it has a foreground service with an associated notification.