Unity Collaborate verifies that the version of Unity used for the update that you are publishing matches the version of Unity used to published the latest update shown in the Collab History window. If the version does not match, Unity displays the following warning:
Your version of Unity has changed. This will impact other members of this project.
To ensure that there are no conflicts in features and functionality, all team members should use the same version of the Unity Editor. Additionally, when a team member opens a project from a previous version of Unity in a more recent version, Unity updates the Project files to the new version. These files might not be compatible with earlier versions of Unity.
When a new version of Unity becomes available, it is important that all members of the team are able to upgrade at the same time.
For more information on the impacts of upgrading a Unity project, see the Unity Upgrade Guides.