Product gallery, variant images and thumbnails
Check product list image, gallery and zoom separately. The zoom file does not have to be loaded in full size for each category tile.
Compare product main image, gallery and the image of the selected variant. In block themes, the gallery component determines its presentation; classic customizer settings do not automatically apply to every gallery block.
Where to check the setting in WooCommerce
Open product image, gallery and the image of the affected variant. Check the specific image reference and your media library information. When changing variants, the new image output must also have a suitable alternative and a reserved display space.
Example of this specific finding
Illustrative control case: A product tile with 360 CSS pixels wide loads the 4,000 pixels wide original. What matters is the variant loaded in the network protocol, not the file name in the CMS.
follow-up audit in WooCommerce
Change gallery and variant selection mobile test. Actually check loaded size, alternative text and reserved area for each view.
For multiple screen widths, check the selected image URL, file size and sharpness. On high-resolution displays, higher natural resolution may make sense.
Derogations and scope
A detailed view with Zoom may require larger files than a preview list. Balancing quality and transmission effort against actual use.
Regarding: WooCommerce on WordPress. Block and classic product templates as well as SEO extensions can have different output locations.
Classify the general error
Definition, system-independent causes and further correction examples: Check image weight, output size and subject together
Configuration and test signal documentation
WooCommerce: Product Images and Galleries