Images must have alternative text
Why it matters
Screen-reader users hear nothing (or a file name) for these images, so products and banners are invisible to them.
How to fix
Give every meaningful image alt text. In Shopify themes, render alt from the image object with a sensible fallback.
<img src="{{ image | image_url: width: 800 }}" alt="{{ image.alt | default: product.title | escape }}">
Example element
<img src="data:image/svg+xml,%...">