Steps to reproduce

1. Create instance of telegram.Bot with token
2. Create instance of telegram.ext.Default with parse_mode=telegram.ParseMode for example
3. Then create Updater with the instance of telegram.Bot and telegram.ext.Default

Expected behaviour

Default parse_mode should be telegram.ParseMode right?
Please confirm if it's intended behaviour, or not.

Actual behaviour

Default parse_mode is None

Configuration

Operating System: WSL2 Ubuntu

Version of Python, python-telegram-bot & dependencies: python3.8, python-telegram-bot==12.4.2

Thanks.