It's clearly stated in the documentation : https://www.ventoy.net/en/plugin_vtoyboot.html
For facilitate identification and processing, you MUST change the file suffix to .vtoy. This is mandatory.
So you can not set the name of the Linux vdisk as manjaro.vhd you must set the name as manjaro.vhd.vtoy
For Ventoy, .vhd file is always treated as Windows VHD file.
For Ventoy, only .vtoy file is treated as Linux vdisk file.
For facilitate identification and processing, you MUST change the file suffix to .vtoy. This is mandatory.
So you can not set the name of the Linux vdisk as manjaro.vhd you must set the name as manjaro.vhd.vtoy
For Ventoy, .vhd file is always treated as Windows VHD file.
For Ventoy, only .vtoy file is treated as Linux vdisk file.