Why it matters
Variants that serve 200 create duplicate sites, and multi-hop redirects (http → https → www) waste crawl budget.
How to fix it
Redirect every variant (http, www or apex) to the canonical https origin with a single 301/308. On Vercel, set the non-canonical domain to redirect to the primary.
References
More seo rules
void seo reports 60 rules in this category. What search engines need from the raw response: status codes, titles and descriptions in <head>, self-referencing canonicals, one h1, crawlable links, Open Graph, icons, robots.txt and a sitemap with real dates.
soft-404Missing page returns HTTP 200 (soft 404)html-too-largeUncompressed HTML is over Googlebot's 2 MB fetch limitrsc-payload-ratioInline RSC flight payload dominates the HTMLnot-httpsPage served over plain HTTPhtml-lang<html lang> missing or not a valid BCP 47 tagviewportViewport meta missing, not device-width, or blocks zoomcharsetCharacter encoding not declared earlytitle-missingNo single non-empty <title> in <head>