I get this error when I enable Advanced Mode. PHP version 7.4, WordPress version 5.7.
Notice: WP_Scripts::localize was called incorrectly. The $l10n parameter must be an array. To pass arbitrary data to scripts, use the wp_add_inline_script() function instead. Please see Debugging in WordPress for more information. (This message was added in version 5.7.0.) in .../wp-includes/functions.php on line 5313