Your sitemap is lying to Google

A sitemap is a list of the URLs you want crawled and when they really changed. A lot of sitemap effort goes into two fields Google ignores, and the one field it does use is often wrong.

The fields Google ignores

Google's sitemap documentation says it ignores <priority> and <changefreq>. Setting every page to priority 1.0 and "daily" does nothing.

The field it uses, if you're honest

Google does use <lastmod>, but only when it is consistently and verifiably accurate. A sitemap that stamps every URL with the time the file was generated tells Google every page changed today. It takes Google very little time to learn that your dates mean nothing.

Google spelled this out when it retired the sitemap ping endpoint in 2023: lastmod should reflect the last significant change to the page's content, not a copyright year or a sidebar widget.

Other common problems

• URLs that shouldn't be there: redirects, 404s, pages marked noindex, and duplicates that point their canonical somewhere else. A sitemap should list only canonical URLs that return 200 and can be indexed.
• Too big: one sitemap file holds at most 50,000 URLs or 50 MB uncompressed. Bigger sites need a sitemap index file.
• Nobody can find it: add a Sitemap: line to robots.txt so every crawler knows where it is, not just the search engines you submitted it to.
• Still pinging: the ping endpoint is gone. Submit the sitemap in Search Console and list it in robots.txt instead.

The fix

Generate the sitemap from your real content: canonical, indexable URLs only, with lastmod set to the date the page's content last changed. Drop priority and changefreq. Declare it in robots.txt.

The free Sitemap Inspector (my own product) finds your sitemap, checks the XML, counts the URLs, and checks lastmod freshness and the robots.txt declaration.