This is a very simple, dumbed-down version with direct step-by-step instructions.
It may not make sense to you but it does to me. If it does help you, however, please share.
Copy the following into functions.php of the child theme, or into a shortcode plugin.
add_filter( 'gutenberg_use_widgets_block_editor', '__return_false' ); add_filter( 'use_widgets_block_editor', '__return_false' );