The Information investigated and found that OpenAI has been answering queries that rely on realtime info by getting Google Search data via SerpApi.

The Information's article is gated for subscribers only, but you can read an ad-riddled summary in Tom's Guide.

Side note, visited SerpApi's website and they have a really nice top nav on desktop - crams in a lot of links without friction or overwhelm. Their mobile top nav is good but expected. Also you can do a free test search if you want to see how their tool works.