Using Open Suse Tumbleweed (20230917 snapshot, also happened on the 20230916 snapshot):
Game displays the following error: “Our Servers Are Experiencing Additional Load Due To Unusual Levels Of Traffic”.
Troubleshooting steps taken:
firewalld was disabled (to troubleshoot connectivity issues)
Installed Windows version using Proton-GE 8.15
Linux client cannot login. Using Proton-GE 8.15 allows the game to function normally.