When Thanos punches Tony in the trailer he doesn’t lift his right arm. Do you think maybe his right arm has failed him mid battle? It’s been teased that his arm had been damaged from civil war

Maybe, I thought it was his left arm that was damaged in CW though?

Either way, the body frame is just all wrong for it to be Tony. And in a situation like that? Where Tony is literally fighting for his own life and Peter’s, and everyone else on Earth? Unless his arm was torn off, I’m pretty sure the fight and survive instinct would kick in and he would raise that arm regardless of injury.