Yes, this could be so. People rely on the visual information, so if the style doesn't align with what they expect of the story in their mind, they might have problem with that. As a personal example, my characters are 9-14 year old kids in the first season (the time skips every season), my style is colorful and something that a lot of people call "cute", so I got a couple of comments like "if this is a horror story what's up with kid friendly art". A quick panel with no empty talk
Welp... nothing to do here. You can still change the whole visual mood of the story to suit the heavier plot ( deeper colors, cooler angles, etc). If you like your style, there's nothing too bad about people not getting its appeal within the genre. If you think you better advance your style into something more mature, you can do that too. But it's up for you to decide, there will always be people who will have some problems with what you draw and how you draw it, so try to not lean on these opinions too much. You do you.
If you're afraid some parent on this site could think your story is a great kids comic and then will be angry at you - the probability of this is incredibly low, so don't worry 