The String.prototype.normalize function does not work in Mongo 8 when executing Server Side javascript

Please help because I am facing problem with usage Server Side javascript (I am aware that it was deprecated in version 8).
But as I undrestand correctly the String.normalize static function support was removed but the prototype form should still work.

Maybe it is problem with my javascript knowledge but when I am trying to execute below function:

const getUnicodeNormalizeName = function (developer){
return developer.normalize(“NFC”);
}

In aggregate pipeline:

const options = { ordered: true };
const developersTeam = [
{ t_id: “t1”, developer : “Mike”},
];
await arraysCollection.insertMany(developersTeam, options);
const expectedTeams = [JSON.stringify({t_id: “t1”, name: “Mike”})];

  // WHEN
  var result = await arraysCollection.aggregate([{
                                                    $addFields: {
                                                        name: {
                                                            $function: {
                                                                body: getUnicodeNormalizeName.toString(),
                                                                args: ["$developer"],
                                                                lang: "js"
                                                            }
                                                        }
                                                    }
                                                }
                                                  ]).toArray();

Then I get such exception:

MongoServerError: PlanExecutor error during aggregation :: caused by :: TypeError: developer.normalize is not a function :

Full code is on github: