That’s the beauty of the algorithm. It’s not just time of day, but what you’re doing and where you are. Look for other common threads, like anytime you’re near a gym, or if you’re browsing an online store. Assume they know literally everything about you in the moment.

Of course, there are other plausible explanations. Maybe you are sometimes connected to wifi with a pihole that blocks the ads? Maybe your cellular connection is spotty and the app is compensating with music already on your device? Maybe there’s a quota that they are supposed to hit, and any blocked ads are queued up for later until you connect again? Like I said, I don’t know what’s causing it.