You are absolutely right!  I contacted QB again via chat and found a tech who DID know what he was talking about. The reason the checks were "modified" was to make them available for payroll cloud services. And YES, QB is supported until May 31, 2022. 

I only wish I had an opportunity to let QB know how demeaning that first tech was, by name, and how he talked down to me when I was right all along. One of my worst tech support contacts EVER. Thank you for validating what I was saying.