As of 19th October 2023 both Windows 7 and Windows 8 are no longer supported for Vermintide 2.
This change is neccessary for Vermintide 2 going forwards, due to these OS versions no longer being officially supported by Microsoft, and with Windows 7 and Windows 8 support ending for Steam in January 2024.
Please see this related Steam Support article:
We can only advise our players currently using Windows 7 and Windows 8 to update to Windows 10 or Windows 11.