Thanks for your message, I would be happy to offer you some assistance with this. This looks like your theme is re-arranging the product images, rather than re-sizing them, this looks like it is native to your theme as many times when you switch a theme to a mobile view it will need to optimize your site for that size change. What theme are you using for your shop? If you are using a third-party theme, your best bet would be to reach out to the developers of your theme to take a look, however, this may not be something that can be changed natively and may require coding by a Shopify Expert or local developer.
Please feel free to reach back out here with any further context or questions, we are always happy to chat!
Marty | Social Care @ Shopify - Was my reply helpful? Click Like to let me know! - Was your question answered? Mark it as an Accepted Solution - To learn more visit the Shopify Help Center or the Shopify Blog