I feel like this film suffers from a bad case of not knowing what it wants to be. The kids are designed and act like edgy steven universe characters, which doesn't mesh well with the very goofy caricature of the neighbor Hitler. The way the characters interact with each other and respond to their situations emotionally is confusing and inconsistent. A lot of the jokes don't land as a result. It hits this awkward middle ground where I'm not sure whether a scene is trying to be serious or funny or ironic. Honestly the only real laugh I got was at the very end of the film when you guys decided to finally embrace the ridiculousness of the situation by having hitler draw big ol' feet. That was one of the funniest jokes I've seen in a while.
Also the animation is pretty bad at times. There were moments where a character would be missing their nose, or their walk made no sense, or the perspective was off. It became distracting at times just how weird or bad some sequences were, especially because those scenes contrasted with some really nice art and animation.
Overall, it's pretty good, just not great. Especially for how much time and effort went into it from a couple of skilled animators, it seems a bit disappointing. I hope you guys figure out your style a bit more for whatever comes next.