The primary duty of your manuscript is to be understood by readers. Using overly complex language to sound scholarly only serves to make your writing harder to understand. This error is very tempting, as this is likely one of the most important manuscripts you have written, but remember, you are writing it to educate and inform. The more straightforward you can be, the more your audience will take away from your research.
Example from the Simon Fraser University: “Often after entering the world of academia, students assume the need to showcase their understanding of a subject through their writing by using extensive and supposedly eloquent prose and vocabulary, in a pursuit to assimilate themselves into and join the ranks of those they view as highly intelligent beings: academics.”
Replacing this sentence with "Students often use flowery language as a strategy to sound more professional in their papers" is much easier to understand and better gets the point across.