The dividing line is a count, not a feeling: how many of your pages are stalled, one or many. That single number tells you whether you are looking at a content problem on a page or a trust problem across a domain, and it is the first thing to settle before you change anything.
Here is the test. Search site:yourdomain.com to see how much is actually indexed, then check the stalled pages against the rest of the site. If one page or a handful are stuck while everything else indexes normally, the problem is local to those pages. The signal gets sharper if pages on your easier, less competitive topics index fine, since that rules out the domain and points the finger at the specific page that will not go in. If instead large swaths are excluded, including pages that should be easy wins, the issue has moved up a level to the site itself.
The two problems take different fixes, and using the wrong one burns weeks. A page-level stall is a content problem: the page is too thin, too similar to others, or simply not yet worth a slot in Google’s eyes, so you make that one page genuinely more useful and distinct. A domain-level stall is a trust problem: Google is deprioritizing the site as a whole based on overall quality and history, so the work is wider, cutting thin and redundant pages, lifting the average quality of what remains, and earning the authority that makes Google want to index more of you.
What you cannot do is hide behind either label to dodge the other. “It’s just domain trust” is an excuse when the real issue is a weak page you could fix this afternoon, and “it’s just this page” is denial when half the site is sitting in the excluded pile. Count first. Then fix the level the count actually points to.