Berserk is dark, this is just blood and a leg missing that apparently left a black hole, you gotta be pretty young and or naive to think this is dark. Even the "kid" that got stabbed is just a clone, and they made sure of that
This is like the care bears for the kids of today. The things they see on youtube for example can be way more graphic than this and it has real people. For example, a Shakira music video has more adult content than Boruto anime.
Naruto Shippuden wasn't even dark. Pt.1 Naruto? Sure, somewhat. But Naruto Shippuden? I can hardly think of a scene that would fall into that category. Boruto definitely has dark themes, like cannibalism for example.