It's not an issue of sideloading or censorship in iOS. It's a product decision related to background apps (they kill the running process with no recourse to bring it up again on its own).

As I understand it, only Apple's own apps get the magical blessing to run in the background whenever they want.

Hmm, seems anti-competitive.

Anti trust enforcement was tried briefly at the turn of the century but was deemed unprofitable for oligarchs, so it is no longer in fashion.

Eh, it has seen a mini resurgence recently

In Europe it's been ruled that since Apple makes no pretense of being competitive, they don't have to be, while Google has to actually deliver on their open platform promises.

This affects other Bluetooth-using apps too, like the Fitbit app needs to be periodically restarted in order to get data synced from a tracker.