I accidentally misgender trans people all the time. Never have I ever been accused of being transphobic because I handle it like calling someone the wrong name accidentally. I quickly correct myself and move on, and actively do my best to remember their pronouns going forward.
Sure, it takes half a braincell of effort at first, but then it becomes easier. This is a strategy known as “not being a dick”.
That said I call everyone Carl because I’m too lazy to learn everyone’s name, and I don’t want to walk on eggshells to make sure I don’t call someone the wrong name accidentally./s