Hallucination
When a model states something false or invented with the same confidence as a fact.
Hallucinations happen because models predict plausible text, not verified truth. Applied to your brand, that can mean a wrong price, a feature you do not offer, or a confident claim with no basis.
Grounding and good source material reduce the risk. Monitoring matters too, since the only way to catch a hallucination about your brand is to look for it.