Edit. The error was found. The reason is the presence of Cyrillic letters in the user name.
So the question changes to another one. How, if possible, to make the game work with Cyrillic in the user name? It is possible to change the user name, but it is inconvenient for a number of reasons. It's just that earlier the game worked perfectly with this. I just really don't understand how it works. One moment the game was fine with it, the next moment it wasn't.