@pascal are you talking about Excel reports?
The cron expression should be evaluated against the server timezone AFAIK (it uses the timezone from the OS/JVM by default, you can override this in your env.properties file).
Are you sure you don't have your server timezone set to UTC?
What is the behavior of the CRON expression when DST (daylight saving time) adjustments apply
Good question. Our cron code is based on the Quartz scheduling library v2.1.0, so this should help -
Of course if its actually evaluating the expressions as UTC time then there is no DST.