How To Disable Widget Block Editor In WordPress 5.8+

functions.php

// Ref: https://wpcodeus.com/disable-widget-block-editor-in-wordpress-5-8/

/**
* Disable Default Lazy Loading In WordPress
* In order to disable widget block editor in WordPress by default, 
* you need to add the following code into your themes functions.php file.
*/

// Disables the block editor from managing widgets in the Gutenberg plugin.
add_filter( 'gutenberg_use_widgets_block_editor', '__return_false' );

// Disables the block editor from managing widgets.
add_filter( 'use_widgets_block_editor', '__return_false' );