Why does the container provide UTC time after I have set the time zone on my app?

When changing time zones for your app, the underlying time applied to the container isn't changed. Instead, the server registers the change in the app time zone as an adjustment from UTC. 

UTC is the default timezone for all logs, for some services, timezone can be changed (but again it doesn't impact logs).

For more information on this feature, please see the following page in the Upsun documentation:

https://docs.platform.sh/projects/change-project-timezone.html