I noticed too. Would anyone care to share on how to do this.

Oh that's an interesting question. Following

Try reaching out to Google support. Also make sure you follow all their steps - https://support.google.com/merchants.../6324350?hl=en Here is a little information below and check you Diagnostics page.

"Minimum requirements
These are the requirements you'll need to meet to show your product. If you don't follow these requirements, we'll disapprove your product and let you know in the Diagnostics page in your Merchant Center account.

Use a URL that points to an image in a supported file format.
Start with http or https and comply with RFC 3986. For example: http://www.example.com/image1.jpg.
Replace any symbols or spaces with URL encoded entities. For example, if your URL contains an ampersand ( & ), then replace it with %26. If your URL contains a comma ( , ), then replace it with %2C.
Make sure your URL can be crawled by Google. For example, ensure your robots.txt file is configured correctly. Learn more about robots.txt files
Submit only one value. Only one value will be accepted for this attribute, and any subsequent entries will be ignored. If you want to submit multiple images, you can provide these using the additional image link [additional_image_link] attribute. "

yea I've noticed that too, it's a good idea to have images under your content as it makes your content more interesting. I don't know the exact way but I think it will appear by posting a picture or putting a link at the end or wherever you want to show that image.