Does ChatGPT Browser mode use an automated browser?

When using the new Browsing mode on ChatGPTA, it seems to use some sort of headless browser. Anyone know exactly what they use?

I don't get why they don't use bing search API, or make some other arrangement with M$ to access their search index?

It seems like a very inefficient way for a computer to perform millions of web searches. And it's certainly extremely flaky to use.