Microsoft.EntityFrameworkCore.Design contains all the design-time logic for Entity Framework Core. It’s the code that all of the various tools (PMC cmdlets like Add-Migration, dotnet ef & ef.exe) call into.
If you don’t use Migrations or Reverse Engineering, you don’t need it.
And when you do need it, we encourage PrivateAssets="All" so it doesn’t get published to the server where you almost certainly won’t need it.