Hard to understand logic in core archiving

Hi,

This is an example output for our archiving:

DEBUG [2020-10-04 08:03:18] 1 process_new_segments_from set to segment_creation_time, oldest date to process is 2020-08-26
DEBUG [2020-10-04 08:03:18] 1 Start date of archiving request period (2015-10-12) is older than configured oldest date to process for the segment.
DEBUG [2020-10-04 08:03:18] 1 Archiving request date range changed to 2020-08-26,2020-10-04 w/ period week.
INFO [2020-10-04 08:03:19] 1 Will pre-process for website id = 1, period = week, date = last260

First, " Start date of archiving request period (2015-10-12)". Where does this date come from? There is no data from that date - our Matomo setup for this client were setup in march 2019 - and no old logs have been imported.
And “Archiving request date range changed to 2020-08-26,2020-10-04” <= this does not make sense together with the rest of the debug output.