Beyond album art, a Roon controller instance will additionally cache metadata, session history, and navigation information. Clearing the Roon cache from Settings won’t delete this data in its entirety.
The team can certainly investigate diagnostics on the affected device, but we’ll require more verbose logging from the Roon iPad controller on the iPad Air 3 itself. At your convenience, please find the iOS section in the directions found here and send over a set of logs to our File Uploader.
In the meantime, try fully uninstalling and reinstalling the app on the affected iPad, deleting data fully. What is the storage draw on fresh reinstall?
A less heavy-handed test would be to monitor whether storage fluctuates over time.