Why array_reverse sorting columns?

[chuoke]

Hi, I encounter the Unstable Pagination problem.
I want to solve it by adding the id to sortable like this ->sortable(['updated_at', 'id']). But what happened was that the actual order by comes like this order by id desc, updated_at desc.

Why? I checked the code and I found this code in applySort method:

        foreach (array_reverse($this->getSortColumns()) as $sortColumn) {
            $query->orderBy($this->getSortColumnForQuery($query, $sortColumn), $direction);
        }

I want to know why we need reverse sorting columns. This is very unconventional.

Thanks!