my website crashes when I upload my own created plugin.

The code looks like this:

Plugin.php

/**
 * Plugin Name: Plugin Test
 * Description: Test
 * Version: 1.1
 */

 function price_plugin_menu(){
    add_menu_page('Test Plugin', 'Test Plugin Menü', 'manage_options', 'test plugin', 'page_content', 'dashicons-games', '1');
}
add_action('admin_menu', 'test_plugin_menu');
function page_content(){
    echo '<div class="wrap"><h2>Test PLugin</h2></div>';
}


add_filter('wc_ff_vaibale_output','my_wc_ff_vaibale_output', 10, 3);
function my_wc_ff_vaibale_output($variable, $element, $element_uniqueid){
    
    if ( $element_uniqueid === '62488f701db0a7.13260453'){
        $variable = array();
        $variable[0] = "111";
    }
 
    return $variable;
}

When I run the code under functions.php, it works. The function wc_ff_vaibale_output in the filter is from another plugin.

What am I doing wrong?