Use new eleventyExcludeFromCollections feature in 0.8.0: https://www.11ty.io/docs/collections/#option%3A-exclude-content-from-collections

404.md

@@ -1,7 +1,7 @@
 ---
 layout: layouts/home.njk
 permalink: 404.html
-excludeFromSitemap: true
+eleventyExcludeFromCollections: true
 ---
 # Content not found.
 

feed/feed.njk

@@ -1,6 +1,6 @@
 ---
 permalink: feed/feed.xml
-excludeFromSitemap: true
+eleventyExcludeFromCollections: true
 ---
 <?xml version="1.0" encoding="utf-8"?>
 <feed xmlns="http://www.w3.org/2005/Atom">

feed/htaccess.njk

@@ -1,6 +1,6 @@
 ---
 permalink: feed/.htaccess
-excludeFromSitemap: true
+eleventyExcludeFromCollections: true
 ---
 # For Apache, to show `{{ metadata.feed.filename }}` when browsing to directory /feed/ (hide the file!)
 DirectoryIndex {{ metadata.feed.filename }}

sitemap.xml.njk

@@ -1,16 +1,14 @@
 ---
 permalink: /sitemap.xml
-excludeFromSitemap: true
+eleventyExcludeFromCollections: true
 ---
 <?xml version="1.0" encoding="utf-8"?>
 <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
 {%- for page in collections.all %}
-{%- if not page.data.excludeFromSitemap %}
   {% set absoluteUrl %}{{ page.url | url | absoluteUrl(metadata.url) }}{% endset %}
   <url>
     <loc>{{ absoluteUrl }}</loc>
     <lastmod>{{ page.date | htmlDateString }}</lastmod>
   </url>
-{%- endif %}
 {%- endfor %}
 </urlset>