Before Chrome 88, Cumulative Layout Shift did not take shifts of descendents of sticky elements into account. This has been fixed in Chrome 88. Source code for this change.
Prior to Chrome 88, Cumulative Layout Shift did not take shifts of fixed position elements into account. This has been fixed in Chrome 88. Source code for this change.
content-visibility: auto feature was shipped in Chrome 85, a CLS-impacting flaw was present: changes between the skipped and not-skipped state of a
content-visibility: auto subtree caused an observed layout shift in the
content;visibility: auto element as it resized.
In Chrome 88, the CLS issue was fixed. Going forward, there should be no CLS penalty for such elements. (Note that there still may be a layout shift for onscreen elements adjacent to (but not descendants of) the
content-visibility: auto element.
We have been always ignoring layout shifts when the element has visibility:hidden. However before Chrome 89, if the element having visibility:hidden became visible and shift at the same time, we reported layout shift. Now we also consider the previous visibility and ignore layout shift in the case. Source code for this change
All of these changes only affect sites with specific types of content. Here are the specifics for each change:
Sites with descendents of sticky position elements which shift unexpectedly should see an increase in their Cumulative Layout Shift scores.
Sites with fixed position elements which shift unexpectedly should see an increase in their Cumulative Layout Shift scores.
content-visibility: auto should no longer see any impact of this feature on their Cumulative Layout Shift scores, resulting in a decrease in their scores.
Sites using visibility:hidden to hide layout changes may see a decrease in their Cumulative Layout Shift scores.
A bug was introduced in Chrome 86 in which Cumulative Layout Shift was measured incorrectly for certain cases involving nested out-of-flow elements (absolute-position or fixed-position). This caused reported shifts even in some cases where there was not actually a shift.
Chrome 88 is currently scheduled to be released the week of January 19, 2021.