Intrusive Interstitial
Google's term for a popup or overlay that covers the main content, especially right after a mobile visitor arrives from search, and can affect a page's ranking.
Google Search Central describes intrusive interstitials as overlays that make content less accessible, with a specific focus on mobile pages reached from search results. The documented examples are a popup that covers the main content immediately after arrival, a standalone interstitial the user must dismiss before reaching the page, and a layout where the above-the-fold area looks like an interstitial while the content sits below it.
The same guidance lists what is not treated as intrusive: interstitials required by law such as cookie consent or age verification, login dialogs for content behind a paywall, and banners that use a reasonable amount of screen space and are easy to dismiss. The distinction is size and timing, not the existence of a popup.
For a marketing popup the practical rules follow directly. Do not fire a full-screen overlay on load for mobile organic visitors. Prefer exit intent, scroll depth, or a time delay, use a floating bar or slide-in where a modal would cover the content, and keep the close control obvious. The signal applies per page, so entry pages from search deserve the most care.
See it in practice