1.Ovf file is exported from vmware workstation 15

So we get 3 files:
(1)Ubuntu_64_bit-disk1.vmdk;
(2)Ubuntu 64 bit.mf;
(3)Ubuntu 64 bit.ovf;

2.Using qemu-img to convert ovf files to vhdx

qemu-img.exe convert D:\ubovf\Ubuntu_64_bit-disk1.vmdk -O vhdx -o subformat=dynamic D:\test_dir\dest.vhdx

3.Create a new virtual machine in hyper-v

Create a new virtual machine, attaching existing vhdx hard disk files, and select generation 1 only. The source vmdk virtual machine should be legacy bios machine, so generation 2 can not be started.
Then start and connect to the VM.

Reference:

1. https://cloudbase.it/qemu-img-windows/
2. https://learn.microsoft.com/en-us/windows-server/virtualization/hyper-v/plan/should-i-create-a-generation-1-or-2-virtual-machine-in-hyper-v