Qt 6.1 introduces https://doc-snapshots.qt.io/qt6-6.1/qvulkaninstance.html#supportedApiVersion which now allows requesting API versions 1.1 or 1.2 via https://doc-snapshots.qt.io/qt6-6.1/qvulkaninstance.html#setApiVersion in a sensible manner.
Now, what should Qt Quick request? (when using the default path of letting the Qt Quick scenegraph create a VkInstance)
The default is API version 1.0. This is good enough for most things but is not future proof. For example, if we start using VK_IMAGE_CREATE_2D_ARRAY_COMPATIBLE_BIT, which is a Vulkan 1.1 constant, in the near future, then at minimum the validation layer's warnings - and in the worst case the whole behavior of the Vulkan implementation - will get affected (in a bad way) due to only requesting API 1.0 on the VkInstance.
Therefore, the scenegraph's VkInstance creation should check if > 1.0 versions are available, and if so, request API 1.1.