Post featured image sizing problem

I’m confused as to why some featured images on my posts are true to the scale of the image and other images are cropped.

Here is an example of the featured image being rendered fine: https://www.executivecoachinglifecoaching.com/small-business-owner-speeding-towards-burnout/

Same scare for the uploaded image (and it does show correctly on the Blog page), but it’s cropped on the post page: https://www.executivecoachinglifecoaching.com/challenge-your-limiting-beliefs/

I imagine it’s something I’m doing, but I cannot figure out what that could be.
Thank you for your help.
Emma