The security.kmip.kmipKeyPollingSeconds parameter was added in MongoDB 5.3 (thus also 6.0).

This doesn't appear to be documented in the server configuration options.

Code link: https://github.com/10gen/mongo-enterprise-modules/blob/61170464d1be36d2dfd3969f9ed4837010bf78fd/src/kmip/kmip_options.cpp

Related ticket for polling implementation: https://jira.mongodb.org/browse/PM-1348

Server configuration documentation page: https://www.mongodb.com/docs/v6.0/reference/configuration-options/