When is the date of publication of this patent?

Invention patents, utility models and designs are all different. The publication date you mentioned should be the publication date of the invention patent and the authorization announcement date of the utility model and design patent, because the invention patent is subject to substantive examination, and the invention patent will be made public and published in the patent bulletin before entering the substantive examination procedure. The patent for utility model and design does not go through the substantive examination procedure, so the authorization announcement date is the public day.