Does Classic Editor resize feature images?

Recently, my images crop when I set them as featured (not just crop with css, but actually create a cropped image for the featured image, so that if you get the image location and go to it its a cropped image). I don’t want this, as it ruins my images and messes with my social sharing. I don’t know what’s causing it. I have Classic Editor installed on the site it happens on. Is it a part of Classic Editor?