The Publish button shows what's happening, and domains get a DNS checklist
Publish shows a spinner while it builds and a badge when you have unpublished changes or a domain needs attention. Domains checks each DNS record one by one, and you choose the primary address.
Publish now shows its state at a glance: a spinner while your site builds, and a badge when you have changes that aren't published or a domain needs attention.
Domains checks each DNS record on its own and shows what it found next to it, so you can see which record is missing. When a project has more than one address, you choose which one is primary, and the others redirect to it.