After Google announced Gemini 3 as the default model for AIO on 1/27, SEOers started noticing AIOs with no cited sources. Google said it was a bug and they'll fix it.

SE Ranking analyzed 100K keywords across 20 niches (US market only) at 4 points in time: 3 of them before Gemini 3, one of them after. They confirmed that since the Gemini 3 announcement:

• AIO appear less frequently
• Over 10% of AIO cite no sources at all (previously .11%)
• Almost half of all cited domains are not cited anymore
• The most commonly cited domains are pretty much unaffected (YouTube, Reddit, Facebook, etc)
• The number of unique domains getting cited decreased by 14%

Since the bug is not fixed yet they say they'll analyze more data after Google says it's fixed. But in the meantime if you notice fewer AIO citations for a domain, this could be part of why.