When I search Google with site:subdomain.example.com" keyword1 keyword2 keyword3", it shows only one image as a preview. However, a specific page on the same site, like https://subdomain.example.com/keyword1-keyword2-keyword3/, shows three preview images for the same query. Why does this happen?
I have more than 3000 products & pics on my site, and all products have been imported with the same method. So, for all pics, pic name has been generated to include keywords, I have set alt text, title, caption, and description. I also can see all images are indexed on Google images, so this seems not to be a indexation issue.
Why is the result aleatory? What should I do to fix it?