I mean, it is a teaser trailer at the end of the day. I don't imagine the whole show will be like this. Plus some people are acting as if the show was 100% lighthearted which... no? If it has the same balance of tone just with an edge due to no Nickelodeon restrictions, it won't necessarily be a bad thing. It just depends on how it's executed.
For example, I like that they're showing the Air Nomad genocide in this which is something they never would have gotten away with in the animated show.