File: /wp-admin/includes/class-pclzip.php contains this commented out line of old WordPress code below that was replaced 6 years ago. I cannot tell you anymore than that. You would have to ask Wordfence if they are detecting this commented out line of code by mistake and have them fix that bug in Wordfence.
Code line 4067: // eval('$v_result = '.$p_options[PCLZIP_CB_PRE_EXTRACT].'(PCLZIP_CB_PRE_EXTRACT, $v_local_header);');