Why it matters
A lastmod that changes on every build tells crawlers every page changed every time. Google learns to ignore the site's lastmod entirely, so real updates stop getting priority recrawls.
How to fix it
Use the content's real update date (frontmatter updated, CMS updatedAt, a hand-maintained date) — never build time.
Example
posts.map((p) => ({ url: `${site.url}/blog/${p.slug}`, lastModified: p.updated }))References
More lint rules
void lint reports 67 rules in this category. Static source checks with no browser: Tailwind v4 silent failures, Next.js 16 API traps, React render-body bugs, accessibility markup, SEO files and motion hygiene.
missing-llms-txtNo `/llms.txt`dynamic-metadata-streamingRequest-time `generateMetadata` without `htmlLimitedBots`missing-langRoot `<html>` without `lang`jsonld-missingNo JSON-LD structured datamultiple-h1More than one `<h1>` in a route's page + layoutsjsonld-deprecated-typeJSON-LD type that no longer produces rich resultsroute-js-budgetRoute first-load JS over budget (from `.next` build output)animate-undefined`animate-*` class with no matching `--animate-*` theme variable or `@keyframes`