I just realized while using VK_MAKE_VERSION that it has been deprecated. The deprecation message recommends using VK_MAKE_API_VERSION instead. The only difference between them is that the latter has an additional variant parameter.
I know what the major, minor, and patch mean, but I never saw a variant version before. What does it mean?
This is explained in section 30.2.1. Version Numbers of the current Vulkan specification:
The Vulkan version number comprises four parts indicating the variant, major, minor and patch version of the Vulkan API Specification.
The variant indicates the variant of the Vulkan API supported by the implementation. This is always 0 for the Vulkan API.
Note
A non-zero variant indicates the API is a variant of the Vulkan API and applications will typically need to be modified to run against it. The variant field was a later addition to the version number, added in version 1.2.175 of the Specification. As Vulkan uses variant 0, this change is fully backwards compatible with the previous version number format for Vulkan implementations. New version number macros have been added for this change and the old macros deprecated. For existing applications using the older format and macros, an implementation with non-zero variant will decode as a very high Vulkan version. The high version number should be detectable by applications performing suitable version checking.