School holidays in 2022 are in mid April, I have checked and started making bookings around the dates. The lack of rewards post 25/26 is most likely to doe with the Northern summer/ winter schedule change and there have been threads (one I started), posts in the SQ threads about rewards flights not being available towards the end of March. As by chance I called QF yesterday to see if I could get seats released to JP in early Apr 22 and was advised that their schedules post 26 Mar 22 are not yet loaded. These are some other threads:I'm guessing the awards have been blocked after that date due to school holidays.
QS not publishing flights sin syd
SQ Tips Trips and Tales
What is the significance of the Northern Winter and Summer Schedules