Godzilla saw the pollution that Humanity was causing, all of the habitat they destroyed and animals they slaughtered just because they got in the way of their stupid development, and Godzilla had enough of them, he thought that he should have destroyed them long ago, but he wasn't going to let this continue, as he declared war on Humanity, he no longer cared about his role as a protector, he only wanted to save the planet from Humanity and the grasp of pollution