How do I fix Discovered – currently not indexed in Google Search Console?

Community question: See the title above for the specific issue and context.

Practical answer

This status usually means Google knows the URL but has not crawled it yet. Check server availability, internal links, crawl accessibility and the volume of low-value URLs. Remove duplicate or unwanted URLs from the sitemap and make important pages easy to reach from relevant pages. Monitor crawl activity and allow time for Google to revisit.