This workaround did the trick for me: https://github.com/derekantrican/GAS-ICS-Sync
This did it for me! Thanks very much.
And the benefit is also that I have more control over the synchronization process from Microsoft Outlook to Google Calendar. For example on the interval, which normally is like 24 hours, and can now be set to for example 15 minutes.
This really is a Google Calendar problem, because you want to edit this time zone within Google Calendar. But because there is interaction and differences with Microsoft Outlook, of course this is also on their side. But not being able to adjust the time zone in Google Calendar makes it their problem, because it's their product.