If you mouseover an item on the main page, it will say “next review is in about X hours”. Previously, this would round to the nearest hour, now it rounds down. So e.g. if it is currently 5:50 am and you have a review due at 8pm, previously it would have said “review in about 14 hours”, but now it says “in about 15 hours”.
Obviously, the change doesn’t really break anything, and the new system is arguably more sensible, but I was still surprised to see it.