I have the same problem. Exactly the same message as the screenshot from the OP. I have several other VMs running off a zfs pool, and I cannot install Windows 10 2004 .iso. The virtio drivers just won't succeed during installation. I verified SHA's several times between the host sha and Microsoft's own expected sha. So this is not a corrupt ISO. Same with Windows 10 1909. Running Proxmox 6.2 with latest non-subscription updates and kernel.
Here's my VM config (redacted the virtio MAC as it injects unwanted images and doesn't add value). I tried all - scsi (below), virtio, even sata. Watched Proxmox's narrated video example and read the best practices several times. There has to be some bug or non-obvious misconfiguration here.
agent: 1
bios: ovmf
bootdisk: ide2
cores: 32
efidisk0: aorus:vm-102-disk-1,size=1M
ide0: local:iso/virtio-win-0.1.189.iso,media=cdrom,size=488766K
ide2: local:iso/Win10_2004_English_x64.iso
machine: q35
memory: 32768
name: win10
net0: virtio=[redacted],bridge=vmbr0,firewall=1
numa: 0
ostype: win10
scsi0: aorus:vm-102-disk-0,cache=unsafe,discard=on,size=250G,ssd=1
scsihw: virtio-scsi-pci
smbios1: uuid=5de116e6-4f0c-498e-982b-b5fafbfa13cc
sockets: 1
vga: vmware
vmgenid: 06c83d97-8ca7-4ff8-8645-b3d8be43de5e