They ship with several firms, I've seen 12.0.1, 12.0.2, 12.0.3, and 12.1.0 (and have dumps of 12.0.2 and 12.0.3), and they're all special variants that differ from what N released on the CDN to normal units.
It fixes the known crash that happens if you've put a marker on a particular door at the end of the game. Apparently has some other small unspecified improvements. You'd be fine without it, assuming you don't happen to put a marker on that specific door.
I am pretty sure they are wrong on what God desires from us lowly humans though lol pretty sure a deity would be like "Man I am too busy for this shit just be cool to each other and handle the small crap yourself"