When I watched «Spider-Man: No Way Home», I was very surprised when (during the battle with the Green Goblin in the apartment) Otto just ran away, without even trying to return and help Peter. Like many viewers, I thought it was just a "lazy script". You know, "We want a cool fight between Spider-Man and the Green Goblin, so we will remove all people who could help Peter in this fight." But today I remembered something. Do you remember how Dr. Octavius became the villain in Spider-Man 2? He was electrocuted. Because of this, his chip was broken, and the AI of his tentacles took control of his mind. What happened in «No Way Home» in that scene? Otto wanted to help, but Electro struck him with lightning! Only after that, Otto ran away. Why? Here's my explanation. He was scared that Electro might break his new chip! This guy took back control of his mind just a couple of hours ago, and of course he doesn't want to lose control again! Of course he panicked, anyone would panic in his place.
And it is not surprising that when Otto returned to the scene of the final battle, he neutralized Electro. Not the Lizard, not Sandman, but Electro. Because the electricity had already destroyed his life once.