According to the Salesforce Platform API Versions 21.0 Through 30.0 Retirement document:
As of the Summer '22 release, the following Salesforce Platform API legacy versions have been deprecated and are no longer supported by Salesforce.
What is changing?
Customers can continue to access these legacy API versions until Summer '23 is released, which is when these legacy versions will become retired and unavailable. When versions 21.0 through 30.0 are retired, applications consuming these versions of the API will experience disruption as calls will fail and result in an error indicating that the requested endpoint is not found and unable to be processed by the platform.
How does this impact Zuora CPQ Package users?
As stated in the Notes section of the Salesforce article: “This retirement does not include Custom Apex REST & SOAP Web Services, Apex Classes, Apex Triggers, or Visualforce Pages.”
We have reviewed the Zuora CPQ package compatibility and have come to the conclusion that there is no impact to any version of the Zuora CPQ package by the scheduled API version deprecations coming in the Salesforce Summer ’23 release.
The Zuora CPQ Package only uses Apex Classes, Triggers, and Visualforce pages, other than use of the SOAP API, Version 33, for legacy PDF generation, which will be unaffected by this Salesforce Release.
For more information, see Key Dates for the Summer ‘23 Sandbox Preview.