The fact that we're citing a mural from some no-name artist who doesn't even have a Wikipedia page as the "backlash" suggests that there is very little backlash.
Dak was asked about it again by reporters at Cowboys practice in context of him receiving criticism. It's clearly a thing. It's one of ESPN's top headlines, Shannon Sharpe blasted him on ESPN, there are memes all over the internet implying that he's Uncle Tom. If you want to argue that the backlash is coming from people that don't matter, I agree, but when this was first brought up on these boards some people were calling the backlash #fakenews and saying only twitter bots were saying anything about it.