They tried to prosecute him. In MAGA world, that demands an escalation in kind to attack (“defend”) against the prosecution; the truth or falsehood of the accusation doesn’t matter. They also think Biden stole the election, although as before, they don’t really care in an objective sense whether that’s actually factually true. They believe it wholeheartedly and that’s all they care about.

There’s also a fiction that “they” are trying to put kitty litter in your classrooms and tell your kids to pretend to be cats and pee in the litterbox, or allow transgender people into women’s bathrooms because someone “became transgender” for that exact purpose, or other weird and outlandish things, but I don’t think those are really getting traction as much as they’d like them to. I think it’s mainly a standard sociopath pattern of “I did an illegal thing” -> “You’re reacting as if it’s illegal” -> “My god how could you make that wild accusation and be an enemy to me” -> “I attack you”.