@Dierkens at this point the "Desktop" software upgrade that sales is referring to here is not a desktop software in the traditional sense. You still must have a subscription in order to access your file. At this point if you upgraded to Sonoma and your Quickbooks is now broken you can wait it out for the new Sonoma release patch and hope it fixes it, you can pay for a new Quickbooks and pay for it in perpetuity, you can restore your computer to a Time Machine backup prior to your upgrade to Sonoma, you can install a virtual machine and then your version of Quickbooks on there and restore your Quickbooks from a backup. 

I hope this helps.