@kk-siemens See https://learn.microsoft.com/en-us/nuget/reference/cli-reference/cli-ref-trusted-signers#nuget-trusted-signers-sync--name-name and https://haacked.com/archive/2019/04/03/nuget-package-signing/

Reference: NuGet/Home#11605

@kk-siemens does the above solution provide by @lindexi resolves your query?

I don't know what to add as parameter in
nuget trusted-signers sync -Name

BTW: I tried the build.cmd on different computer and it worked well there

Executing command "dotnet nuget trust list" (or "nuget trusted-signers list") to get trusted signers:

On computer where it doesn't work:
Registered trusted signers:

1. xUnit.net (.NET Foundation) [author]
   Certificate fingerprint(s):
   [U] SHA256 - 0D7662406AABB78B853A1901343BF9F7757492B785402172C5962D8204408161

On computer where it works:
There are no trusted signers.

@kk-siemens Can I find your %appdata%\NuGet\NuGet.Config and %ProgramFiles(x86)%\NuGet\Config\NuGet.Config files? Does some info record in the two NuGet.Config files?

"%ProgramFiles(x86)%\NuGet\Config\NuGet.Config" doesn't exist

"%appdata%\NuGet\NuGet.Config":

<?xml version="1.0" encoding="utf-8"?>
<configuration>
<packageSources>
<add key="nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" />
</packageSources>
<activePackageSource>
<add key="nuget.org" value="https://www.nuget.org/api/v2/" />
</activePackageSource>
<trustedSigners>
<author name="xUnit.net (.NET Foundation)">
<certificate fingerprint="0D7662406AABB78B853A1901343BF9F7757492B785402172C5962D8204408161" hashAlgorithm="SHA256" allowUntrustedRoot="true" />
</author>
</trustedSigners>
<config>
<add key="signatureValidationMode" value="accept" />
</config>
</configuration>


@kk-siemens Thank you. Emmm, how about replace the content of "%appdata%\NuGet\NuGet.Config" to

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <packageRestore>
    <add key="enabled" value="True" />
    <add key="automatic" value="True" />
  </packageRestore>
  <bindingRedirects>
    <add key="skip" value="False" />
  </bindingRedirects>
  <packageManagement>
    <add key="format" value="1" />
    <add key="disabled" value="False" />
  </packageManagement>
  <packageSources>
    <add key="nuget" value="https://api.nuget.org/v3/index.json" />
    <add key="Microsoft Visual Studio Offline Packages" value="C:\Program Files (x86)\Microsoft SDKs\NuGetPackages\" />
  </packageSources>
</configuration>

And you can backup the origin "%appdata%\NuGet\NuGet.Config" before you replace the content.

If you can not fix this issues by replace the content, that I guess the environment variables may record the error value. See https://learn.microsoft.com/en-us/nuget/consume-packages/consuming-packages-authenticated-feeds