If you are using the Gutenberg page builder for your pages and posts, you should avoid using Saved Layouts. See here more info about Visual Portfolio Blocks.
To reuse blocks, you can use the built-in Gutenberg feature – Reusable Blocks.
Saved Layouts may be only used for 3rd-party builders only (such as Elementor, WPBakery Page Builder, etc). Since WordPress moved from Shortcodes to Blocks system, we prepared for you advanced blocks.
In case if you don’t use the Gutenberg block editor, you may create a Saved Layout and insert it on your pages using a shortcode.
There is also a helpful shortcode for WPBakery Page Builder and widget for Elementor, which will let you select one of the available Saved Layouts and output it.