We were only sending one silent notification every two hours, which is less than the limit described in the docs, which say not to send more than two or three silent notifications per hour.But we absolutely need to perform a background sync within that two-hour period due to the functionality of our app, and there doesn't appear to be a reliable way of doing that anymore.

Debugged this with Apple support, and turns out background app notifications are now completely unreliable for background sync purposes, since about 95% of all our users simply don't receive them for a variety of reasons, such as "not enough memory" or other system resource limits.I guess before iOS13, these limits weren't as strict or as thoroughly enforced, but now, it's at a point where using silent notifications is just pointless, as some users get them consistently, but most either never get them or get them once in a blue moon.Going to try the new background tasks introduced with iOS13, but given that the old device-initiated background sync basically ran whenever it wanted and without any consistency, I'm not holding my breath.Seems there's just no way to reliably ensure background sync anymore.