If you get this error and you target only android or ios environment please check your project file and delete this code block.
<ItemGroup Condition="$(TargetFramework.Contains('-windows'))">
<!-- Required - WinUI does not yet have buildTransitive for everything -->
<PackageReference Include="Microsoft.WindowsAppSDK" Version="1.0.0" />
<PackageReference Include="Microsoft.Graphics.Win2D" Version="1.0.0.30" />
</ItemGroup>