No HTML possible on Hashnode (which is not a bad thing)
All images are always aligned to the left for me, if they are too narrow (which is sometimes annoying)
There is no image zoom for big images, which had to be scaled down, so I usually have to manually add a link around the image, so people can click that to see the original in a new tab. These scaled-down images often look terrible!
The preview works a little different than the rendered text; especially code rendering after saving an edit is broken. Maybe the code base is not DRY enough?