OK, so the crash dumps were not immediately helpful because the leak is happening outside of the managed code. For now, it does not look like the issue is in our code - but it is really hard to diagnose since leaking is unmanaged memory. However, the leaked memory content seem to contain lots of SQL Server stuff (column names, stored procedure parameters and such), which prompts to ask all of you the following question - do you use local or remote SQL Server?
I know most of you in this thread are affected by the issue, but I also saw one confirmation on the other thread that someone else did not have any problems after installing the update. So, if we can confirm that all of you affected have local SQL Server installed on your backup server, and those who are not have remote SQL Server - this will be a big step forward in the investigation.