Here are the following advices for designing the leading edge blanking of a flyback converter. There is also the schematic:
It tells us that there is reverse recovery current which occurs from the output rectifier diode, I suppose or from the snubber diode (which is not represented on the schematic). If they are considering the output reverse recovery current of the rectified diode I do no think that It will be high as in general the primary has a higher turn number than the secondary. (There is reverse recovery diode only in CCM mode, no?)
It does not mention about primary leakage inductance too? If the flyback works in CCM mode it should have an influence on the voltage spike, no? By contrast, it mentions about leakage source inductance.