To maintain compatibility with QuickBooks Desktop for Mac 2019, you should avoid updating your macOS from Sonoma to Sequoia, @amg_buyer. I'll provide more details so you can continue using the program.
As mentioned, updating the Sonoma to Sequoia can affect the compatibility of the desktop version you used. Therefore, I recommended keeping your current operating system to ensure being free from error whenever you use the program to record transactions and perform other QuickBooks activities. Moreover, you can work with an IT personnel for other available options or to help you with your settings to avoid update prompts from the system.
On the other hand, you'll want to ensure you can secure a backup copy of your company file. This way, you can restore it while keeping all your data available. Explore this article for more details: Back up your QuickBooks Desktop for Mac company file.
I highly encourage you to comment below if you have more questions about QuickBooks or require assistance completing tasks. As always, I'll be around to extend a helping hand. Keep safe.
