since a few weeks already I am trying to fix my CLS issues. My sitemap contains of 150 single pages in total. All of those 150 pages are affected by BOTH the Mobile and Desktop CLS issue (>0.25 & >0.5).

Taking a look at the Lab Data all pages are good, CLS and performance-wise. Also, working with the Web Vitals Chrome Plugin it doesn't show me any issues even when interacting for minutes with the site.

Has someone a different approach/way to find CLS issues?

  • Since Core Web Vitals are measured when real users visit your site (by CrUX reports), check if location or device of your visitors could have played a role.
    – Kannan
    Jun 9, 2021 at 13:45
  • Thanks @Kannan. I have thought of this already before and switched the devices. However, still can't locate the potential issue of the Layout Shifts.
    – PG3
    Jun 9, 2021 at 20:44

1 Answer 1


If you aren't able to detect the CLS issue using lab tools, then the issue is likely the results of user interactions or device/network combinations that you might be aware are common.

I wrote a guide, Debugging Web Vitals in the field that explains how to use your analytics tool to detect what could be causing the CLS issue with your field data.

I also gave a talk at Google I/O that covers how to use this technique with Google Analytics 4, which you might also find useful.

I hope that helps!

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