Incorrect date format after upgrading to macOS Ventura

I have just upgraded my MacBook Air to macOS Ventura.

In the System Settings I have selected "Netherlands" for the Regional settings. But the date format is wrong. When I click on the popup menu, I can only select between these formats:

29/08/2022

2022-08-29

Please note that the date separator for the first choice is wrong. It should be "-" instead of "/".

I can not find any way to change this. There used to be an "Advanced" button here in previous versions of the OS for further customisations. But that button is now missing.

Does anyone have advice?