Textarea blacklist not working.

I think that within efas_is_field_value_exist_in_string strpos function is being called with the arguments exchanged:

function efas_is_field_value_exist_in_string($string, $field_value) {
    if ($string === "" || $field_value === "") {
        return false;
    }

    $string = strtolower($string);
    return strpos($string, strtolower($field_value)) !== false;
}

Should be:

return strpos($field_value, strtolower($string)) !== false;