Hi I found some issues in your sample
configuration flag with env you set like dotnet pack src/proj/proj.csproj -o ./artifacts --configuration ${{env.config}}
env.dotnet_core_version to 6.0.x to download latest security updates of .NET 6 env.DOTNET_CLI_TELEMETRY_OPTOUT and env.DOTNET_SKIP_FIRST_TIME_EXPERIENCE are not necessary and you can remove them. this is my test