Searched here and reddit and google and found no one else mentioning this, so I hope it's not too foolish a question...
I've noticed this with 2 apps so far: Vanadium and Podverse, a podcast app I got from F-Droid. If the screen locks, including if I do it manually, it seems the app functions normally; in the case of Podverse, audio continues to play and I can play/pause from the lock screen. But once I unlock the phone--or more specifically, once I unlock the phone and bring the app to the foreground/focus--it resets. Podverse displays the splash screen and loads up again, and audio stops; in the case of Vanadium, I can briefly see the tab I had open, but then my home page loads, and all background tabs are gone.
I tried changing background data and unrestricted battery use for these apps just in case, but I didn't notice any change from that. Does someone have suggestions or a direction to point me in for troubleshooting? Thanks so much.