Google’s John Mueller said on Twitter that mobile intrusive interstitial elements won’t generally impact indexing but it can have a ranking impact. This goes back to the old Google Intrusive Interstitials Mobile penalty from 2016/2017.

John said “the intrusive interstitial element has a ranking effect, it wouldn’t affect indexing.”

This is in response to Lily Ray asking if Google would not index something because it may have triggered the mobile interstitial penalty? The answer was no. Here are those tweets:

The intrusive interstitial element has a ranking effect, it wouldn’t affect indexing. I’d check if the content is actually rendered in HTML or it’s perhaps otherwise technically hard to reach.

— 🧀 John 🧀 (@JohnMu) August 17, 2021

The conversation does go on with more debugging:

My guess is it’s not a technical issue (interstitials in general as mentioned, and if some of them are getting indexed). Soft-404 would be another guess, but I imagine you checked. Other ideas: server speed, content demand, overall quality, meteors taking out nearby datacenters.

— 🧀 John 🧀 (@JohnMu) August 17, 2021

So no, the Google mobile interstitial penalty does not impact Google indexing.

Forum discussion at Twitter.