If I ask natural language yes/no questions, Gemini sometimes tells me outright lies with confidence.
It also presents information as authoritative - locations, science facts, corporate ownership, geography - even when it's pure hallucination.
Right at the top of Google search.
edit:
I can't find the most obnoxious offending queries, but here was one I performed today: "how many islands does georgia have?".
Compare that with "how many islands does georgia have? Skidaway Island".
This is an extremely mild case, but I've seen some wildly wrong results, where Google has claimed companies were founded in the wrong states, that towns were located in the wrong states, etc.