This may well be the case, that the A380 will operate SQ228. But there is still an error in the schedules, as it is physically impossible to send an aircraft away full of passengers before it even arrives - unless they plan sitting the 773 on the ground for 23:55 min .... unlikely. I guess they haven't updated the 773 schedules yet, and Soorox 's suggestion would make a lot of sense.

BTW the A380 change is still not showing in online commercial bookings through the SQ website But is for redemptions and third party bookings.