Horizontally stretched images

Hi,

We have noticed that our images are automatically stretched to be full width, for example https://www.partiv.com/top-20-hojeste-bygninger-i-danmark/ and https://www.partiv.com/53-bike-touring-adventurers-reveal-favorite-destinations/

Anyone know how we can insert images in our posts/pages, so they aren’t stretched?

The two images above are inserted like this:

width=”800″ height=”5034″ class=”aligncenter size-full wp-image-2974″

width=”800″ height=”17547″ class=”alignleft size-full wp-image-7786″

Thanks,
Mads