Building the class which has a static field and two or more private methods, private methods will be overwritten by the last one.

class T {
  #a() { return 'a'; }
  #b() { return 'b'; }
  static c;
  d() { console.log(this.#a()); }
}

The d() is expected to return 'a', but it returns 'b'.
Here is the output code

...
  var _a, __create, _b, __create;
...
  _a = new WeakSet();
  __create = function() {
    return "a";
  };
  _b = new WeakSet();
  __create = function() {
    return "b";
  };
...

__create is declared twice, and the first __create is overwritten by the next one.