It not important that the problem is from PUBG side. Well there is one way, you can use VPN and see if the problem solved or not! You can use the solo VPN and follow these given step by step it will surely work!

1: Close the PUBG KR Game on iOS

2: Now go to Apple Store and Download Fastway VPN for iOS

3: Now choose the South-east Asia Region like “South Korean Server” from the VPN app and connect to the Server.

4: Now open the Game and Login to your ID the Game will run without any Issue

5: After the game is loaded, toggle back to VPN app and Disconnect it or else your Ping will reach the greater height

[Source]https://www.gadgetlite.in/2021/01/how-to-fix-pubg-kr-server-maintenance-in-android-ios/