CloudKit Private Database Record Zone Limit

I am following this document from Apple to implement sharing with CloudKit. In it, Apple says

NSPersistentCloudKitContainer uses CloudKit zone sharing to share objects. Each share has its own record zone on the CloudKit server. CloudKit has a limit on how many record zones a database can have.

What is the record zone limit for a private CloudKit database?

I can find information about record and participant limits but not on record zone limits.

Can anyone provide an empirical lower bound?

CloudKit Private Database Record Zone Limit
 
 
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