Cumulative Layout Shift (CLS) refers to unexpected change in the position of content on a page, and usually happens because resources are loaded asynchronously or DOM elements get added to the page above existing content.
CLS is problematic if it occurs when the user is actively using the page. It can cause the user to click or press something else if they are trying to interact with the page, or might cause them to lose their place if they are reading an article.
But is CLS relevant in the case where it’s obvious that the page is still loading? Can a shift in the page’s layout still lead to a bad UX?
I am referring to the case where the user will see a spinner as well as potentially a dark overlay over the page. While the problems described above may not happen, I am wondering if CLS may still cause confusion due to elements momentarily being rendered in a location which is not their final location.