Currently, when Chrome loads a placeholder image (e.g. for Client-side LoFi), it'll download the entire response even if the server ignored the range request header and sent the entire image.

Typically, Chrome only needs a small number of bytes at the beginning of the image resource to decode the image dimensions and create a placeholder image, so once those conditions are met, Chrome might be able to cancel the request to save the user some amount of the yet-to-be-downloaded resource data.