Sorry for the daft question, but what do you believe happened on 7 October? Do you think it wasn't as horrific and savage as all that because rape kits etc weren't deployed in the chaos of identifying charred and dismembered bodies? Do you think that the wild jubilation in the streets of Gaza (Shani Louk's mangled naked body being paraded and spat on comes to mind, but there are plenty of other videos) were staged? Are you aware that the attacks were carried out not just by Hamas, but by mobs of Gazan civilians? Do you know that they did far worse things to dead, dying, and living women than dance in their underwear?
Because Gaza-based militant groups had fired over 18,000 rockets and mortars at Israel since Israel’s withdrawal from Gaza in 2005, the IDF thought they had things under control by dealing with these (e.g. Iron Dome) and underestimated Hamas's capacity to carry out a land invasion. You can see from videos of Nova Festival that no one really batted an eyelid at first when they found themselves under rocket fire, becuase that's just an ordinary day. (Imagine that at Glastonbury!) It's only when they heard gunshots that they began to realise something very different was happening.
In response to the atrocities of 7 October, the IDF mobilised over 300,000 reservists to triple its numbers. Many had not served in years, and some were flown in from abroad to rejoin units. There were also “lone soldiers” – volunteers from abroad without family in Israel – driven by rising antisemitism and solidarity after the attack.
In the context of the deadliest and most sadistic attacks on Jews since the Holocaust, it would be surprising if everyone involved in the aftermath – especially those who had to go into such a terrifyingly hostile environment – behaved like a Designated Safeguarding Lead at a junior school in Kent. I wish none of it had happened, but instances of individuals and groups behaving badly are somewhat understandable in the circumstances.