Help has arrived, @billhdz.

Happy to provide clarifications on the compatibility of these versions in QuickBooks. Thus, the confusion will be eliminated.

Yes, you're correct that QuickBooks Desktop (QBDT) for Mac 2019 and 2020 version is compatible with Big Sur and Monterey. Just ensure that you're in Release 13 to avoid any issues soon. Since you're in the renewed release, I'd suggest installing the update as soon as you're ready. This way, you can utilize the new features.  

But before that, I'd suggest backing up your company file for future use. 

Furthermore, check out our QBDT for Mac Q & A for your later reference. This page contains various topics of QuickBooks that surely answer your frequently asked questions. 

Let me know if there's anything else you need. I'll be right here to help you with your account. Hopefully, I've clarified everything. Take care, billhdz.