From time to time, I’ll continue to return to this thread in hopes that one day it will be closed, because there’ll be a preference setting in Figma turning off this annoying “feature” of having my images arbitrarily scaled down without my permission, or asking my opinion. This has to be the worst bug in Figma. Please fix it.
Hey @Sean22,
We appreciate your feedback and understand your frustration. As mentioned above, Figma has a built in size limit for images of 4000 pixels, so any image larger in either height or width will be down scaled to fit to improve performance.
Because of that, our team considers this as an expected behavior, not a bug. This topic also wasn’t switched to a feature request until March 24th, 2023. We will continue to monitor this thread and pass feedback and interest from the community along to our team for consideration. Be sure to vote and let your friends know to vote too! 
Just voted! I’m also hoping this is a feature added in the next update. It’s frustrating when images are resized smaller and they’re pixelated. Especially for things like comp analyses, when I’m trying to import a screenshot of an entire webpage / experience, and I want to show other designers and stakeholders the full experience of a competitor.
The result is a super small pixelated image that can’t be resized. Not good for presentations or showcasing professional work.