I think for world wide this could have a lot to do with it, but this poll was solely in America. It’s been my experience (not everyone’s, just mine) that even if some people lump trans people with lgb and write them off as “weird gays”, most just leave them alone and want to be left alone by them. Is that homophobic? Yeah, I’d say. But it doesn’t explain why the rate of acceptance has dropped each year or leveled at the lower rate, not increased, for the past few years.

As for the aggression and hostility- I do believe that that, in addition to many other issues, contributes to the decline. I agree that visible and known trans people need to call out allies- they also need to call out other trans people when they take things to far, and they often need to be called out themselves.