Sorry, but this doesn't address the question or help at all. It's not a matter of requirements -- it's a bug in your software we've been told would be addressed for almost 2 years. Perhaps you can ask the development team or support engineers this:

Does QuickBooks 2021 (Desktop, not subscription) edition still have a bug that causes the installation of SQL Server 2012 to interfere with being able to use/save to-do items/reminders? 

A direct and definitive answer to this question would be greatly appreciated.