BioRender is cool for premade vector images, but their license (and cost) is still too prohibitive for that, especially for grad students. Bioicons (https://bioicons.com) is a nice FOSS alternative.
Edit: Looking closer the title is deceiving, making posters seems like a new feature, but not the core purpose. Making figures seems to be the main purpose of this product, and that is a lot closer to a core activity for scientists than posters are. Still very expensive, but I could see a lab buying a license or two, mostly for the large library of icons/components.
Overall, when I was doing a data model chart for my current company, I researched good options for doing that in a collaborative manner, and all of them are subscription-based now, which doesn't make sense for making a diagram or two when draw.io is available.