When you are creating a new Linux or FreeBSD VM, you have to change the default way that disk VHDX is created on Hyper-V host.
New-VHD -Path D:\Hyper-V\Templates\Template-Linux-blocksize-1MB.vhdx -SizeBytes 40gb -Dynamic -BlockSizeBytes 1mb
For Linux VHDX we need to change the BlockSize parameter to 1mb, by default Windows use 32mb.
Like we can see on the image the difference in a little Linux installation is almost 400MB. Could you image how this can affect a Database Server on Linux?