.net5: System.Security.Principal.Windows.dll missing after publish

I have a .net 5 solution that consists of several projects.
Now i had to add the nuget package System.Security.Principal.Windows to one of the projects to be able to do a windows impersonation.

The solution compiles, everything works in the debugger.
But after the publish (to Filesystem) the System.Security.Principal.Windows.dll is missing in (has not been copied to) the publish-folder.

The targetframework is set to net5.0-windows for all projects.

.csproj of the project that will be published:

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>net5.0-windows</TargetFramework>
    <RollForward>Major</RollForward>
    <StartupObject>My.Special.Service.Program</StartupObject>
    <AssemblyVersion>7.0.0.0</AssemblyVersion>
    <FileVersion>7.0.0.42</FileVersion>
    <Version>7.0.0.42</Version>
  </PropertyGroup>
...
  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">
    <PlatformTarget>x64</PlatformTarget>
  </PropertyGroup>

  <ItemGroup>
    <SupportedPlatform Include="windows" />
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.Authentication.Negotiate" Version="5.0.17" />
    <PackageReference Include="Microsoft.AspNetCore.Buffering" Version="0.2.2" />
    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="5.0.17" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="5.0.17" />
    <PackageReference Include="Microsoft.Extensions.Hosting.WindowsServices" Version="5.0.1" />
    <PackageReference Include="Serilog.AspNetCore" Version="5.0.0" />
    <PackageReference Include="Serilog.Extensions.Logging.File" Version="2.0.0" />
    <PackageReference Include="Serilog.Sinks.Seq" Version="5.1.1" />
  </ItemGroup>
...
</Project>

.csproj of the project that requires system.security.principal.windows:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net5.0-windows</TargetFramework>
    <RollForward>Major</RollForward>
    <RootNamespace>My.Special.Service.ComAccess</RootNamespace>
    <AssemblyName>My.Special.Service.ComAccess</AssemblyName>
  </PropertyGroup>

  <ItemGroup>
    <SupportedPlatform Include="windows" />
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.Extensions.Logging" Version="6.0.0" />
    <PackageReference Include="Microsoft.Extensions.Options.ConfigurationExtensions" Version="6.0.0" />
    <PackageReference Include="System.Security.Principal.Windows" Version="5.0.0" />
  </ItemGroup>
...
</Project>

And this is the publish-profile:

<?xml version="1.0" encoding="utf-8"?>
<!--
https://go.microsoft.com/fwlink/?LinkID=208121. 
-->
<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <PropertyGroup>
    <DeleteExistingFiles>True</DeleteExistingFiles>
    <ExcludeApp_Data>False</ExcludeApp_Data>
    <LaunchSiteAfterPublish>True</LaunchSiteAfterPublish>
    <LastUsedBuildConfiguration>Release</LastUsedBuildConfiguration>
    <LastUsedPlatform>Any CPU</LastUsedPlatform>
    <PublishProvider>FileSystem</PublishProvider>
    <PublishUrl>bin\publish\Release</PublishUrl>
    <WebPublishMethod>FileSystem</WebPublishMethod>
    <SiteUrlToLaunchAfterPublish />
    <TargetFramework>net5.0-windows</TargetFramework>
    <RuntimeIdentifier>win-x64</RuntimeIdentifier>
    <ProjectGuid>...</ProjectGuid>
    <SelfContained>false</SelfContained>
  </PropertyGroup>
</Project>

What am I missing?