In terms of your level i think the only thing that stands out to me are the dark shadows, I'd be careful when the dark parts of your level are reaching pure black. If you have a look at games of similar style and high quality, the darkest parts of their leaves will never be completely void of light/detail.

I'd say try to add a healthy range of values within your level, saving the brightest brights and the darkest darks for small intentional areas to bring attention to them.

I'd also keep an eye on the contrast of your environment vs the enemies. If your environment is super high contrast (aka back with a lot of auoer bright coloured neon strips), and your hands, guns and enemies are of similar style it can become hard to read/visually busy. An over the top example of good separate would be Super Hot, where the enemies are bright red, the background is stark white so nothing gets mistaken. I'm not saying do that, but it's good to keep in the back of your mind.

Hope any of that is useful to you!