That sounds more like your phone is agressively shutting apps down to save memory and energy. Some brands are known to do this more than others. You should be able to tell your phone not to close that app when on the background.
That might be something with voyager, I agree with the other person that it sounds like the device itself is closing the app due to some sort of battery setting, but if it's not that then it's something at least. I've tried a handful of different lemmy clients now currently using eternity and none of them did what you were describing there.
That or operator error(less likely) such as using the back button to go back to the home screen instead of using the home button or something simple like that
long shot but, if its a samsung, and you installed the app then didn't use it for awhile, it might have "deep sleep"'d it, basically deep sleeping apps can't run in the background, and it does what you are describing on a per app basis.