Iran was shocked by a massive opening blow in the middle of negotiations which allowed Israel to disable many launcher sites and take air superiority in those regions preventing Iran from accessing their full capacity.

Regardless of this, Israel still just couldn't handle sustained pressure from Irans remaining weapons.

Israel started the war with the goal of regime change and destroying Irans nuclear capabilities, they did neither.

If the war starts back, Iran will still have the capacity to overwhelm Israeli defense and Israel will have to rely on another surprise attack, which is much less likely now that Iran has seen their strategy for doing such.

It's in no way an L for Iran, much less a massive one.