perhaps it is continually polling the Roon Core on the Mac Mini even when not in use?
Roon does not do background activity on iOS–shortly after backgrounding Roon or sleeping the device, iOS suspends Roon, and our code is no longer allowed to run.
This is fairly typical for iOS apps (and a big part of why iOS devices get such great battery life)–there are only a few situations where apps are allowed to consume resources in the background, and Roon doesn’t fit into those profiles.
The setting @Ratbert mentioned could drain the battery by keeping the screen from sleeping when the app is in the foreground, but if it is, you’d notice that Roon is keeping the screen awake, too. That setting is really meant for people who have an iPad in a wall mount with continuous power, or a similar appliance-like situation.
For what it’s worth, I have an iPad Mini 2 that I charge about once a week, and I use Roon frequently on it.
Has anything else changed recently that might explain this battery usage?