These placeholders are generated by processing the image on a server beforehand. Generally they create some html, css or svg markup that is served inline. Having to do a separate request for such placeholder is very bad idea.
It's not clear if these placeholders do actually help, especially placeholders with very low quality. In my opinion, they only add visual noise.
I'd focus more on avoiding layout shifts when images load, and serving images in a good format (avif, webp) and size (use `srcset` or `<picture>`).
It's not clear if these placeholders do actually help, especially placeholders with very low quality. In my opinion, they only add visual noise.
I'd focus more on avoiding layout shifts when images load, and serving images in a good format (avif, webp) and size (use `srcset` or `<picture>`).