Google SEO
Best practices — web.dev
Why reserve space for late-loading elements?
Explicit dimensions for images and advertisements prevent layout shifts that frustrate users and worsen CLS.
Further analysis
Use this entry as an audit checkpoint. The cited source establishes the context; the direct answer identifies what to check before choosing an action.
In SFT, this topic relates to Structure. Check whether the signal is visible on the page, connected to the rest of the website and supported by understandable evidence.
Related search terms include CLS, layout shift. Use them to describe the issue in a brief, audit or answer page.
Applying SFT
Structure turns a rule into readable architecture: headings, URLs, structured data, visible content and clear hierarchy.