The weighting is based, ultimately, on the parsing of the sentence derived from training.
For instance, Gemini gave the answer,,"25,000 Ford Rangers were sold in 2025" based on an article which said in response to the question - How many Ford Rangers were sold last year - "25,000 Ford Rangers were sold in 2025 above the level of 2024, making 75,000 in total '.
The website had and cut and paste the answer from a different question - how many more Ford Rangers were sold in 2025 - because when you answer a question the first part of the sentence is usually the answer and the later parts are explanatory.
It is more than likely an AI agent was used to write the website article and this is why hallucinations increase when LLMs feed on their own output.