When responsiveness is enabled and page width is small enough the image proportions are broken:
This behavior also affects both SE apps: Android and iOS. But in case of app you can’t disable it.
I tried viewing this current question in a small window and couldn't reproduce the problem. In this question you use the Markdown syntax for images, while in the linked post, according to a comment, the author used an HTML
img tag with height and width specified. If people stick to the Markdown syntax like you did here, images should be fine. If you need to resize an image display (for example, to work around the fact that the URL size directives on imgur no longer work), I've found that it works better to specify only one of width or height and let the other be dynamic. (I usually specify width, since the problem I'm usually trying to address is something that's too wide for the page.) If you're able to make or propose an edit on that site, try doing that to fix the image for everybody. (I'm not comfortable trying to propose an edit to a post written in a language I do not read, even just formatting.)