Please note that this Support article contains frontend customizations via modifying the legacy Algolia template files, which are deprecated and unsupported by the Algolia Support Team.
For more information, please review this Support article - "Why is modifying Algolia template files for customizations not supported?"
In case the quality of the product image is affected by its size rendering, you can modify the line:
style=“background-image: url(‘${algolia.helpers.mediumImage(hit)}’)”
In the `algolia_instant_search_product.liquid` file, try replacing "medium" with "large," "grande," or "original" to see if this improves the result.