Amount of pymongo threads

I use the following code in db.py to apply a singleton pattern for providing a MongoClient in my application.

When I call one of the methods in my model like create() or readList() vscode shows the following pymongo threads in my call stack. The threads stay in the call stack during the application lifecycle. When I call create() or readList() n times, the amount of threads stays the same. Is this a normal behaviour? I expected that the threads are closed after some time.

screenshot of pymongo threads in Visual Studio Code

The amount of open threads in vs code while using MongoClient confuses me. What is the "normal" behaviour of pymongo regarding the amount of open threads during the application lifecycle?

# db.py# Python packagesimport sys# External packagesfrom pymongo import MongoClientimport importlib.util# custom packagesspec = importlib.util.spec_from_file_location("utils.config", "../utils/config.py")config = importlib.util.module_from_spec(spec)sys.modules["evolveaiUtils.config"] = configspec.loader.exec_module(config)def singleton(cls):    instances = {}    def wrapper(*args, **kwargs):        if cls not in instances:            instances[cls] = cls(*args, **kwargs)        return instances[cls]    return wrapper@singletonclass Db:  db = None  client = None  def __init__(self):    self.client = MongoClient(config.Config.MONGO_URI)    self.db = self.client[config.Config.MONGO_DB_NAME]  def getDb(self):    return self.db# end of db.py

In my data model classes I use db.py like follows:

# model.py# Python packagesimport sys# External packagesfrom bson import ObjectIdfrom pymongo import ReturnDocumentfrom dataclasses import dataclassfrom datetime import datetimefrom enum import Enumimport importlib.util# custom packagesdbSpec = importlib.util.spec_from_file_location("dal.db", "../dal/db.py")db = importlib.util.module_from_spec(dbSpec)sys.modules["dal.db"] = dbdbSpec.loader.exec_module(db)class SourceEnum(Enum):    WEB = "web"    FILE = "file"@dataclassclass SourceData:    id: str    title: str    type: str    importDate: datetime    def getDictionary(self):        return self.__dict__class SourceModel:"""     Source Model / Data Access Object     The class provides create, read, update and delete methods     for source data stored in a MongoDB"""    def create(self, data: SourceData) -> SourceData:        result = db.Db().getDb().sources.insert_one(data.getDictionary())        insertedId = str(result.inserted_id)        data.id = insertedId        return data     def readList(self) -> list[SourceData]:        sourceDataList = []        cursor = db.Db().getDb().sources.find({})        for document in cursor:            sourceData = SourceData(                id=str(document['_id']),                title=document['title'],                type=document['type'],                importDate=document['importDate']            )            sourceDataList.append(sourceData)        cursor = None        return sourceDataList    def delete(self, id: str) -> bool:        _id = ObjectId(id)        result = db.Db().getDb().sources.delete_one({"_id": _id})        return result.deleted_count > 0# end of model.py