"Priors" refers to preconceived beliefs or assumptions about AI capabilities based on past experience with the technology.
The updating of the priors is really hard. The models couldn't do some things one year ago. I mean, image generation was full of spellings or reasoning. You just couldn't have deeper and smarter answers. You couldn't do data analysis. So my impression of it from change, trying it a few months ago, that prior needs to be updated.