Both sandsteinklettern and teufelsturm don't provide time zone info with their timestamps. That's why, both filters assume that they are in the "Europe/Berlin" and localize it accordingly. However, the sink filter doesn't seem to explicitly convert the time stamp to UTC when writing the data base. But the DB shall contain UTC time stamps only.
Please check again, fix and write some test for correct timezone handling
Both sandsteinklettern and teufelsturm don't provide time zone info with their timestamps. That's why, both filters assume that they are in the "Europe/Berlin" and localize it accordingly. However, the sink filter doesn't seem to explicitly convert the time stamp to UTC when writing the data base. But the DB shall contain UTC time stamps only.
Please check again, fix and write some test for correct timezone handling