Wrong time/timezone

Hi,
we have a problem with the time/timezone.

In Administration->Localization we have set the Timezone to Europe/Berlin (which is CEST: Central European Summer Time; GMT+2).
Our modifications and creations all show the right time.

If we use datetool in velocity the time is one hour behinde.

Following command show us, that datetool uses GMT+01:00
$datetool.get('long')

Is this a bug? Is there a way to tell datetool to use the system timezone?

Our wiki runs via docker-compose. there we pass the local timezone to the container.

    volumes:
      - /etc/localtime:/etc/localtime:ro

On the host the timezone is:

[root@wiki2 ~]# date +"%Z %z"
CEST +0200

Greetings
Dominic