Proxmox updates keep a node up to date with the latest stable packages, patch security vulnerabilities, and introduce new features. Each node checks for the latest updates and alerts administrators through emails if there are any available updates. It is vital to keep all Proxmox nodes up to date, especially when security patches are released. Proxmox developers are very prompt in closing vulnerabilities through updates in a timely manner.
The number and nature of updates vary depending on your Proxmox subscription level. For example, a Proxmox free version without a subscription receives the most up-to-date stable updates, while a node with a subscription receives updates that are not so cutting edge and go through an additional layer of testing. Delaying the new package releases for subscription levels creates a buffer to address any issues that may not have been identified during the initial release.
This is not to say that a node without a subscription is not...