Lighthouse Tests Image Tag complains about no width and height

Describe the bug This code, according to many sources, is correctly formatted, and shows no CLS, which is good. There is no defined underlying CSS for this img:

<img srcset="
    /assets/images/photos/someimage-400.png 400w,
    /assets/images/photos/someimage-352.png 352w,
    /assets/images/photos/someimage-320.png 320w,
    /assets/images/photos/someimage-304.png 304w,
    /assets/images/photos/someimage-288.png 288w
    "
    sizes="
        (min-width: 1160px) 400px,
        (min-width: 960px) 352px,
        (min-width: 760px) 320px,
        (min-width: 660px) 304px,
        (min-width: 320px) 288px
        "
    src="/assets/images/photos/someimage-288.png" alt="A picture of something"
>

Problem Lighthouse performance complains that:

“Image elements do not have explicit width and height”.

However, if I insert a width and height into the src"…", the error goes away, but then executing the code ignores all of the srcset/sizes variables and only uses the src, regardless of screen size. I have tried changing the order of the min widths (and even changing them to max-widths). Same problem. I have also tried <picture> tags, but with same result.

Expected behavior

1. No error message for correctly formatted code.

[adamraine]

This is WAI because a layout shift is still possible as the image loads in.

[adamraine]

Based on our documentation and some brief testing, it looks like sizes in srcset and sizes do not explicitly define dimensions for the image element, and therefore don’t prevent layout shifts. This is WAI as far as I can tell.