I used to do the same—just piling up sources without really weaving them together. What helped me shift was learning how to actually synthesize ideas instead of just stacking them. I got a clearer sense of how to do that after going through this guide: https://www.ozessay.com.au/blog/how-to-write-a-literature-review/. It's technically about lit reviews, but a lot of the advice works for essays too. Helped me stop writing like I was just checking boxes.