Why does installing `googletrans` to a `flask_socketio` app give `Invalid async_mode specified`

Question

When I install googletrans into the most barebones flask_socketio server, running the server gives me Invalid async_mode specified.

Here is the basic Flask app:

from flask import Flask
from flask_socketio import SocketIO

app = Flask(__name__)
socketio = SocketIO(app=app, cors_allowed_origins="*")

if __name__ == '__main__':
    socketio.run(app, host="0.0.0.0", port=3001)

It uses this Pipfile:

[[source]]
url = "https://pypi.org/simple"
verify_ssl = true
name = "pypi"

[packages]
flask="*"
flask-socketio = "*"

[dev-packages]

[requires]
python_version = "3.11"

pipenv install and pipenv run python app.py works fine.

How it Breaks

But, if you pipenv install googletrans and pipenv run python app.py, it breaks:

Broken Pipfile

[packages]
flask="*"
flask-socketio = "*"
googletrans="*"

Response

Traceback (most recent call last):
  File "C:\Users\User\Documents\git\flask-socket-test\app.py", line 5, in <module>
    socketio = SocketIO(app=app, cors_allowed_origins="*")
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\User\.virtualenvs\flask-socket-test-RBuOQeqq\Lib\site-packages\flask_socketio\__init__.py", line 187, in __init__
    self.init_app(app, **kwargs)
  File "C:\Users\User\.virtualenvs\flask-socket-test-RBuOQeqq\Lib\site-packages\flask_socketio\__init__.py", line 243, in init_app
    self.server = socketio.Server(**self.server_options)
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\User\.virtualenvs\flask-socket-test-RBuOQeqq\Lib\site-packages\socketio\base_server.py", line 31, in __init__
    self.eio = self._engineio_server_class()(**engineio_options)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\User\.virtualenvs\flask-socket-test-RBuOQeqq\Lib\site-packages\engineio\base_server.py", line 81, in __init__
    raise ValueError('Invalid async_mode specified')
ValueError: Invalid async_mode specified

Is it googletrans or its dependencies?

I looked at what packages googletrans depends on, to see if it was its dependencies or google translate itself.

I froze the requirements of the failing google translate build, removed google translate, and I was left with this pipfile:

[packages]
flask="*"
flask-socketio = "*"
certifi="*"
chardet="*"
h2="*"
hpack="*"
hstspreload="*"
httpcore="*"
httpx="*"
hyperframe="*"
idna="*"
rfc3986="*"
anyio="*"
sniffio="*"

I pipenv uninstall -all'd, installed this, ran it, and it did not throw the anync error therefore the issue is in the googletrans package itself.