Description
Xcode 16 has introduced a new version of the project format. I believe it's mainly to support folder references
From the Xcode 16 release notes
https://developer.apple.com/documentation/xcode-release-notes/xcode-16-release-notes#Project-Management
Minimize project file changes, and avoid version control conflicts with buildable folder references.
Convert an existing group to a buildable folder with the “Convert to Folder” context menu item in the Project Navigator. Buildable folders only record the folder path into the project file without enumerating the contained files. This minimizes diffs to the project when files are added and removed, and avoids source control conflicts with your team.
To use a folder as an opaque copiable resource, the default behavior before Xcode 16, uncheck the “Build Folder Contents” option in the File Inspector. (123729918)
In theory this should allow for faster project generation when using folder references since xcodegen won't need to enumerate all the files in a source folder.
It appears like XcodeProj has already been updated to support the new types in the file format.