The image itself is being inserted as:
<img src="https://i0.wp.com/speedtester01b.host/wp-content/uploads/2019/11/photodune-6252039-web-and-seo-analytics-concept-s-1.jpg?w=640&ssl=1" alt="" class="wp-image-16" srcset="https://i0.wp.com/speedtester01b.host/wp-content/uploads/2019/11/photodune-6252039-web-and-seo-analytics-concept-s-1.jpg?w=1007&ssl=1 1007w, https://i0.wp.com/speedtester01b.host/wp-content/uploads/2019/11/photodune-6252039-web-and-seo-analytics-concept-s-1.jpg?resize=300%2C177&ssl=1 300w, https://i0.wp.com/speedtester01b.host/wp-content/uploads/2019/11/photodune-6252039-web-and-seo-analytics-concept-s-1.jpg?resize=768%2C454&ssl=1 768w" sizes="(max-width: 640px) 100vw, 640px" width="640" height="378">
There are a bunch of images in there now because that’s how WordPress’s responsive images work. It informs the browser that they’re all available, and the browser chooses the right size.
In my case, I’m getting this image: https://i0.wp.com/speedtester01b.host/wp-content/uploads/2019/11/photodune-6252039-web-and-seo-analytics-concept-s-1.jpg?w=1007&ssl=1
And, it loads as: https://cld.wthms.co/HIL8vD
This is actually correct, because that’s the width of the theme’s content column: https://wp-themes.com/twentynineteen/
What appears to be wrong here is actually the length of the caption, it should wrap below the image.
This appears to just be how the theme operates, but there’s only one way to know. Does the image behave any differently if you deactivate the Jetpack plugin?