Currently, the workflow email mentions time which is one hour behind the UI time. The datetime is inserted into the workflow email template with the following snippet:
$workflowHistory.activeStep.approvalDate; format = "yyyy-MM-dd HH:mm:ss"$
The date in the workflow email uses server time (UTC), whereas the date in the UI is according to the browser's timezone. To unify it, use $workflowHistory.activeStep.approvalDatePartitionDefaultTZ$ and set Default Timezone in Configuration according to the user's browser timezone (e.g., Europe/Vienna). This way, daylight saving times are taken into account.