Because Asia is a very broad region, South Korea and Singapore both belong to Asia. Maybe at some times, you are matched with more Korean players, so your ping is around 30, and sometimes you are matched with players near Singapore, so your ping is around 100.
In the future, we will further improve the matching algorithm to make it easier to match people who are close to each other.
But it may not be possible to completely solve this problem, otherwise players will have to wait longer.