Link previews show your picture on the first share
Before, the first person to share a link could see a preview card with no picture while the platform fetched and measured the image. Share images Zarla makes now carry their size, so the card renders straight away, and every share image carries a short description for screen readers.
Pages that fall back to their main photo keep the old behaviour. Choose a share image in the page's settings, or a site-wide default in Settings, to get the first-share picture.