[wp-trac] [WordPress Trac] #62413: WordPress 6.7 Lazy Load Issue Reducing Image Sizes

[WordPress Trac]

#62413: WordPress 6.7 Lazy Load Issue Reducing Image Sizes
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 Reporter:  dooperweb         |       Owner:  joemcgill
     Type:  defect (bug)      |      Status:  reopened
 Priority:  normal            |   Milestone:  6.7.1
Component:  Media             |     Version:  trunk
 Severity:  major             |  Resolution:
 Keywords:  has-testing-info  |     Focuses:  performance
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Comment (by joemcgill):

 Thanks for the detailed testing report, @SirLouen.

 I agree with @youknowriad that we should keep this open for now while we
 investigate how many sites are potentially affected by this change.

 It's correct that this issue is only effecting Chromium browsers, but this
 is because only Chromium browsers currently support the `sizes="auto"`
 HTML spec at this time. It's not necessarily due to a browser bug, but
 rather an intentional decision that size containment is a requirement for
 implementing auto-sizes. For details you can see this
 [https://github.com/whatwg/html/issues/9448 related issue] or read
 [https://ericportis.com/posts/2023/auto-sizes-pretty-much-requires-width-
 and-height/ this detailed explanation] on why auto-sizes essentially
 requires image dimensions.

 We're currently trying to understand how many sites are potentially
 affected by the combination of auto-sizes and overriding img styles in
 ways that cause the default UA stylesheet to kick in here:


 {{{#!css
 img:is([sizes="auto" i], [sizes^="auto," i]) {
     contain: size !important;
     contain-intrinsic-size: 300px 150px;
 }
 }}}

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Ticket URL: <https://core.trac.wordpress.org/ticket/62413#comment:20>
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