@vrandecic good catch! My guess is that this is an issue with the smaller/cheaper model used to serve this. Flash makes a similar mistake in the Gemini app, but Pro doesn't.
IMHO it would be good if Google supported something like community annotations for claims. But right now each generated answer is wholly independent and can't even be saved for later reference it would seem. There are only individual ratings available, which are presumably used for RLHF.
See https://wiki.social.coop and reach out to the TWG or CWG for more!