I have 2 Kobo devices with 32GB onboard storage (no SD card), a Kobo Aura One LE and a Kobo Forma. I have exactly the same books loaded on both devices, both using the kepub format (6,557 books). Additionally, both devices are running the same FW (4.23.15548) and the exact same patches. Finally, the database file (koboreader.squlite) on each device is basically the same size (804MB).
However, the remaining device storage is wildly different between the 2 devices. The Forma shows 17.6GB remaining, but the Aura One LE shows 19.3GB remaining.
Any idea why there's a significant difference in remaining storage for these devices?