Disable Fullscreen Gutenberg

gutenberg-disable-fullscreen.php

<?php
/**
 * Disable Fullscreen Gutenberg.
 */
if (is_admin()) {
    function ca_disable_editor_fullscreen_by_default()
    {
        $script = "jQuery( window ).load(function() { const isFullscreenMode = wp.data.select( 'core/edit-post' ).isFeatureActive( 'fullscreenMode' ); if ( isFullscreenMode ) { wp.data.dispatch( 'core/edit-post' ).toggleFeature( 'fullscreenMode' ); } });";
        wp_add_inline_script('wp-blocks', $script);
    }
    add_action('enqueue_block_editor_assets', 'ca_disable_editor_fullscreen_by_default');
}