Unfortunately, that is the design of the product. The report definitions are stored as XML and the SQL is dynamically generated at runtime from the XML.
But when a Scheduled Task gets created, the SQL gets hard-coded into the scheduled task.
Your other option would be to rebuild the task as a OnceOnly task every week/month, in which case that instance of the task would have the correct dates.
I cannot really say that there is, or is not, a plan to fix it. This is, from my memory, only the second time the limitation has been encountered in production, and the first was a few years ago.
I will certainly send a note to the Product Manager about this scenario
