Block List Override

Drupal provides an extensive list of blocks, many of which you may never use anywhere, and others you won't use in Layout Builder. Block List Override provides a way to manage the available blocks.

Improve UX and system performance by removing blocks that won't be used on your site. Removing blocks from the site-wide block list will have the most performance benefits, but those blocks will no longer appear anywhere in Drupal, neither in the block configuration for each theme, nor in the Layout Builder block list. 

You can also use it to limit the list of blocks available in Layout Builder, where you probably won't want to see blocks used on sitewide pages.