The term "genocide" encapsulates a number of different crimes, the ICC have called out the following crimes charged against Netyanyahu and Gallant (much of the evidence is not public at this time):
‘intentionally using starvation of civilians as a method of warfare’
‘[w]ilfully causing great suffering, or serious injury to body or health’
'cruel treatment, wilful killing or murder, and intentionally directing attacks against the civilian population
crimes against humanity of murder, extermination, other inhumane acts and persecution with respect to deaths and injuries resulting from or associated with the systematic deprivation of objects indispensable to the survival of Palestinian civilians in Gaza.
They go on to say
and
The Rome statute underpins this, we - Europeans - are good at this, we did it before at Nuremberg, Zionists didn't complain that time did they...