A preview of the draft standard will be provided to Participating Organizations, Qualified Security Assessors (QSAs), and Approved Scanning Vendors (ASVs) prior to being finalized for publication. The intent of the preview period is to allow stakeholders additional time to familiarize themselves with version 4.0 of the standard before it is officially launched. An additional request for comments (RFC) for the community to provide feedback on the PCI DSS v4.0 draft validation documents is scheduled for January 2022.”]
Source: https://blog.pcisecuritystandards.org/updated-pci-dss-v4.0-timeline