Google co-founder Sergey Brin, in a rare public appearance over the weekend, told a group of artificial intelligence enthusiasts that he came out of retirement “because the trajectory of AI is so exciting.”

Brin, 50, spoke to entrepreneurs on Saturday at the “AGI House” in Hillsborough, California, just south of San Francisco, where developers and founders were testing Google’s Gemini model. AGI stands for artificial general intelligence and refers to a form of AI that can complete tasks to the same level, or a step above, humans.

In taking questions from the crowd, Brin discussed AI’s impact on search and how Google can maintain its leadership position in its core market as AI continues to grow. He also commented on the flawed launch last month of Google’s image generator, which the company pulled after users discovered historical inaccuracies and questionable responses.

“We definitely messed up on the image generation,” Brin said Saturday. “I think it was mostly due to just not thorough testing. It definitely, for good reasons, upset a lot of people.”

Google said last week that it plans to relaunch the image generation feature soon.

Brin co-founded Google with Larry Page in 1998, but stepped down as president of Alphabet in 2019. He remains a board member and a principal shareholder, with a stake in the company worth about $100 billion. He’s returned to work at the company as part of an effort to help ramp up Google’s position in the hypercompetitive AI market.

In some cases on Saturday, Brin said he was giving “personal” answers, as opposed to representing the company.

“Seeing what these models can do year after year is astonishing,” he said at the event, a recording of which was viewed by CNBC.

Regarding the recent challenges with Gemini that led to flawed image results, Brin said the company isn’t quite sure why responses have a leftward tilt, in the political sense.

“We haven’t fully understood why it leans left in many cases” but “that’s not our intention,” he said. The company has recently made accuracy improvements by as much as 80% on certain internal tests, Brin added.

Brin’s comments represent the first time a company executive has spoken on the Gemini matter in a live setting. The company previously sent prepared statements from Prabhakar Raghavan, Google’s head of search, and CEO Sundar Pichai in response to the controversial rollout.

Here’s what Raghavan said in a blog post on Feb. 23:

“So what went wrong? In short, two things. First, our tuning to ensure that Gemini showed a range of people failed to account for cases that should clearly not show a range. And second, over time, the model became way more cautious than we intended and refused to answer certain prompts entirely — wrongly interpreting some very anodyne prompts as sensitive. These two things led the model to overcompensate in some cases, and be over-conservative in others, leading to images that were embarrassing and wrong.”

Google declined to comment for this story. Brin didn’t immediately respond to a request for comment. 

Brin said Google is far from alone in its struggles to produce accurate results with AI. He cited OpenAI’s ChatGPT and Elon Musk’s Grok services as AI tools that, “say some pretty weird things that are out there that definitely feel far left, for example.”

Hallucinations, or false responses to a user’s prompt, are still “a big problem right now,” he said. “No question about it.”

“We have made them hallucinate less and less over time, but I’d definitely be excited to see a breakthrough that’s near-zero,” Brin said. “But you can’t just like — count on breakthroughs so I think we’re just going to keep doing the incremental things we do to bring it down, down, down over time.”

When asked by an attendee if he wants to build AGI, Brin answered in the affirmative, citing the ability for AI to help with “reasoning.”

Brin was also asked how online advertising will be disrupted considering ad revenue is core to Google’s business. The company has reported slowing ad growth in the last few years.

“I of all people am not too terribly concerned about business model shifts,” Brin said. “I think it’s wonderful that we’ve been now for 25 years, or whatever, able to give just world-class information search for free to everyone and that’s supported by advertising, which in my mind is great for the world.”

He did acknowledge that the business is likely to change.

“I expect business models are going to evolve over time,” he said. “And maybe it will still be advertising because advertising could work better, the AI is able to better tailor it.”

Brin is confident in Google’s position.

“I personally feel as long as there’s huge value being generated, we’ll figure out the business models,” he said.

Beyond AI, Brin was asked about Google’s difficulties in hardware given recent advancements in virtual reality. Google was notoriously early to the augmented reality market with the now-defunct Google Glass.

“I feel like I made some bad decisions,” he said, referring to Google Glass. If he were doing it differently, Brin said, he would have the treated Google Glass as a prototype instead of a product. “But, I’m still a fan of the lightweight” form, he said.

In regard to the Apple Vision Pro and Meta’s Quest headsets, Brin said, “They’re very impressive.”

When asked about how he sees Gemini impacting spatial computing or products like Google Maps or Street view, Brin responded with as much curiosity as anything.

“To be honest, I haven’t thought about it, but now that you say it, yeah there’s no reason we couldn’t put in more 3D data,” Brin said, to laughs from the crowd. “Maybe somebody’s doing it at Gemini — I don’t know.”

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OpenAI executives disputed claims Elon Musk laid out in a lawsuit on Thursday, and said the Tesla CEO is upset that he’s no longer part of the artificial intelligence startup.

“We believe the claims in this suit may stem from Elon’s regrets about not being involved with the company today,” wrote OpenAI Chief Strategy Officer Jason Kwon in an internal memo on Friday that was viewed by CNBC. “It is deeply disappointing to see Elon take this action against a company he helped start, especially given his close collaboration with some of you who are still here working towards the mission.”

Musk co-founded OpenAI in 2015 and stepped down from its board in 2018, four years after saying that AI is “potentially more dangerous than nukes.”

Musk is now suing Microsoft-backed OpenAI and CEO Sam Altman, among others, alleging they abandoned the company’s founding mission to develop artificial intelligence “for the benefit of humanity broadly.”

Since releasing the ChatGPT chatbot to the public in late 2022, OpenAI has become one of the hottest startups on the planet, with a valuation reportedly over $80 billion. The company’s convoluted “capped-profit” structure resulted in Altman being briefly ousted by the board late last year, before an uproar among investors and employees led to his quick reinstatement.

Musk has long wanted recognition for his central role in the creation of OpenAI, and he spent large chunks of the lawsuit telling his version of events. His lawyers said in the suit that Musk was approached in 2015 by Altman and OpenAI co-founder Greg Brockman and agreed to form a nonprofit lab that would develop artificial general intelligence, or AGI, outside of the corporate sphere.

Musk’s attorneys said their client contributed over $15 million to OpenAI in 2016, which was “more than any other donor” and helped the startup build a team of “top talent.” The next year, Musk gave nearly $20 million to OpenAI, which the attorneys reiterated was more than other backers. In total, Musk invested over $44 million into OpenAI from 2016 through September 2020, according to the suit.

Additionally, Musk leased OpenAI’s initial office space “and paid the monthly rental expenses,” the suit said. He was also “present for important company milestones.”

Kwon didn’t dispute Musk’s central role in the early days of OpenAI, but he added some other details. For example, Kwon wrote that Musk at one point indicated he needed “full initial control and majority equity” and later suggested that OpenAI merge with Tesla.

“We did not think either approach was right for the mission,” Kwon wrote.

In the memo, Altman called Musk a hero of his and said the he misses the old version of his co-founder. But he said the company’s mission continues.

While it’s the first time the dispute between the two sides has resulted in a fiery lawsuit, they’ve been at odds for a while.

Before he split with OpenAI, Tesla hired co-founder Andrej Karpathy as senior director of AI. Karpathy returned to OpenAI in 2023. And Musk has been notably vocal in his opposition to OpenAI and its Microsoft partnership in recent years, stating publicly in November that OpenAI had deviated from its original mission.

“OpenAI should be renamed ‘super closed source for maximum profit AI,’ because this is what it actually is,” Musk said onstage at The New York Times’ DealBook conference. Regarding OpenAI’s transformation from an “open source foundation” to a multibillion-dollar for-profit company, Musk said, “I don’t know, is this legal?”

Kwon insisted on Friday that OpenAI is independent and continues to work “to ensure AGI benefits all of humanity.”

Musk’s lawyers didn’t immediately respond to a request for comment.

— CNBC’s Lora Kolodny and Hayden Field contributed to this report

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