Google indexes selectively. "Crawled — currently not indexed" and "Discovered — currently not indexed" are the two statuses that matter most in Search Console, and both usually mean the same thing: the engine did not consider the page worth the storage. Near-duplicate templates, thin category pages and auto-generated variants are the usual population.
Because indexability outranks every other lever — no index, no ranking, no traffic, no revenue — it deserves the first hour of any audit. Check coverage by template rather than site-wide: an aggregate of 85 % indexed can hide a product template at 20 %, which is where the money was.