On this system, the Vulkan support is behaving perfectly:
Operating System: openSUSE Leap 15.4
KDE Plasma Version: 5.24.4
KDE Frameworks Version: 5.90.0
Qt Version: 5.15.2
Kernel Version: 5.14.21-150400.24.33-default (64-bit)
Graphics Platform: X11
Processors: 8 × AMD Ryzen 5 3400G with Radeon Vega Graphics
Memory: 29.3 GiB of RAM
Graphics Processor: AMD Radeon™ Vega 11 Graphics
> vulkaninfo
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VULKANINFO
==========
Vulkan Instance Version: 1.2.133
Instance Extensions: count = 18
===============================
VK_EXT_acquire_xlib_display : extension revision 1
VK_EXT_debug_report : extension revision 10
VK_EXT_debug_utils : extension revision 1
VK_EXT_direct_mode_display : extension revision 1
VK_EXT_display_surface_counter : extension revision 1
VK_KHR_device_group_creation : extension revision 1
VK_KHR_display : extension revision 23
VK_KHR_external_fence_capabilities : extension revision 1
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Do you have the following AMD related packages installed?
- kernel-firmware-amdgpu
- libdrm_amdgpu1
- ucode-amd
- xf86-video-amdgpu