Stylesheets using `rel="preload" as="style"` are now flagged as render‑blocking

[monkeysdocode]

FAQ

• Yes, my issue is not about variability or throttling.
• Yes, my issue is not about a specific accessibility audit (file with axe-core instead).
• Yes, my issue is not answered by other FAQs.

URL

https://creativetouchrotherham.co.uk/

What happened?

Lighthouse has started flagging all our CSS stylesheets as render‑blocking, even though each one is explicitly preloaded using rel="preload" as="style" in the HTML. Two of the stylesheets are also preloaded via the Link response header. Historically Lighthouse has never treated these preloaded stylesheets as render‑blocking, but recent Lighthouse runs consistently list them under “Render‑blocking resources” and attribute LCP delay to them.

What did you expect?

Preloaded stylesheets (rel="preload" as="style" and/or Link: <...>; rel=preload; as=style) should not be classified as render‑blocking. Preload fetches the stylesheet early, and Lighthouse previously recognised this behaviour correctly. I expected Lighthouse to continue excluding these preloaded CSS files from the render‑blocking audit.

What have you tried?

• Verified that all preload tags are present and correctly formed in the HTML.
• Confirmed that the server sends valid Link: rel=preload; as=style headers for the primary and secondary stylesheets.
• Checked MIME types, caching headers, and transfer sizes.
• Reproduced the issue across multiple Lighthouse runs in Chrome DevTools and pagespeed.web.dev
• Confirmed that no recent changes were made to the site’s preload strategy or CSS delivery.

How were you running Lighthouse?

Chrome DevTools

Lighthouse Version

13.2.0

Chrome Version

149.0.7827.116

Node Version

No response

OS

Windows

Relevant log output

[ferakyan2801-debug]

1

[ChristopherPHolder]

It seems like lighthouse is not flagging the preload link, its flagging the style links under them

As this is not something that is added later on and is delived with the initial html it does not really make sense to add preload tags in this case.

[monkeysdocode]

Interesting. So ironically, the bug could've been in earlier versions of Lighthouse and it's now working as it should? Using rel=preload prior to rel=stylesheet has, until now, suppressed any warnings about render blocking CSS. And the site has never used the rel=preload with JavaScript to switch it to rel=stylesheet technique.