I'll clarify the details about QuickBooks' discontinuation and supportability, @ZefX.
The discontinuation policy mentioned in the article you've shared is for QuickBooks users that use QuickBooks Desktop 2019 (all version). They can still use the program after the discontinuation date. However, updates and online services such as the Bank Feeds and payroll can no longer be used.
That said, the discontinuation policy will not be apply to your clients edition since it looks like they're using QuickBooks Desktop Enterprise 2021. For now, the version of QuickBooks that still supported are 2020, 2021, and 2022.
In case your client wants to upgrade to a newer version of QuickBooks, this article will walk through the process: Upgrade QuickBooks Desktop Pro Plus, Premier Plus, or Enterprise.
Furthermore, you can also check our Product Updates page to learn more about the newest news and updates in QuickBooks.
Feel free to swing by anytime you need help keeping your QuickBooks up-to-date. It'd be my pleasure to help. Have a good one!
