As many have said, with reduced F seating there is less chance of multiple avios seats appearing as reward flights.

Unfortunately for popular destinations the use of space releases or GUFs by GGL or high TP golds allow booking into A class which diminishes the chance of reward seats then appearing.

As many use seatspy or similar, so the use of instant expertflyer notifications means that sudden availability of A class seats gets noticed and those seats get snapped up.

It's likely that there will be fewer GUFs and GGLs than there used to be but I doubt that will make much difference to F award availability, especially to places like SIN or MLE.