Deploy as single-file in .net5 with log4net throws exception for config-file

Trying to deploy a console-application written in .Net 5 with log4net as a single-file. Running deployed application throws exception.

Steps to reproduce

• dotnet new console --name TestConsole --language C# (make sure .net 5.0)
• Install-Package log4net
• Program.cs

static void Main(string[] args)
{
log4net.Config.XmlConfigurator.Configure(new FileInfo("log.config"));
var logger = log4net.LogManager.GetLogger("TestLogger");
logger.Info("Hello World!");
}

• log.config (copy always)

<?xml version="1.0" encoding="utf-8" ?>
<log4net>
  <logger name="TestLogger">
    <level value="ALL" />
    <appender-ref ref="console" />
  </logger>
  <appender name="console" type="log4net.Appender.ConsoleAppender">
    <layout type="log4net.Layout.PatternLayout">
      <conversionPattern value="%level - %message%newline" />
    </layout>
  </appender>
</log4net>

• publish (no single file) = works (when running the console application)

dotnet publish -o .\Publish --self-contained true -r win-x64

• publish (no single file) = throws exception (when running the console application)

dotnet publish -o .\Publish --self-contained true -r win-x64 -p:PublishSingleFile=true

excpetion thrown:

log4net:ERROR Exception while reading ConfigurationSettings. Check your .config file is well formed XML.
System.Configuration.ConfigurationErrorsException: Configuration system failed to initialize
 ---> System.IO.FileNotFoundException: Cannot find file. (0x80070002)
   at System.Reflection.RuntimeModule.GetFullyQualifiedName()
   at System.Reflection.RuntimeModule.get_Name()
   at System.Configuration.ClientConfigPaths..ctor(String exePath, Boolean includeUserConfig)
   at System.Configuration.ClientConfigPaths.GetPaths(String exePath, Boolean includeUserConfig)
   at System.Configuration.ClientConfigurationHost.get_ConfigPaths()
   at System.Configuration.ClientConfigurationHost.GetStreamName(String configPath)
   at System.Configuration.ClientConfigurationHost.get_IsAppConfigHttp()
   at System.Configuration.Internal.DelegatingConfigHost.get_IsAppConfigHttp()
   at System.Configuration.ClientConfigurationSystem..ctor()
   at System.Configuration.ConfigurationManager.EnsureConfigurationSystem()
   --- End of inner exception stack trace ---
   at System.Configuration.ConfigurationManager.EnsureConfigurationSystem()
   at System.Configuration.ConfigurationManager.PrepareConfigSystem()
   at System.Configuration.ConfigurationManager.GetSection(String sectionName)
   at System.Configuration.ConfigurationManager.get_AppSettings()
   at log4net.Util.SystemInfo.GetAppSetting(String key)
log4net:ERROR Exception while reading ConfigurationSettings. Check your .config file is well formed XML.
System.Configuration.ConfigurationErrorsException: Configuration system failed to initialize
 ---> System.IO.FileNotFoundException: Cannot find file. (0x80070002)
   at System.Reflection.RuntimeModule.GetFullyQualifiedName()
   at System.Reflection.RuntimeModule.get_Name()
   at System.Configuration.ClientConfigPaths..ctor(String exePath, Boolean includeUserConfig)
   at System.Configuration.ClientConfigPaths.GetPaths(String exePath, Boolean includeUserConfig)
   at System.Configuration.ClientConfigurationHost.get_ConfigPaths()
   at System.Configuration.ClientConfigurationHost.GetStreamName(String configPath)
   at System.Configuration.ClientConfigurationHost.get_IsAppConfigHttp()
   at System.Configuration.Internal.DelegatingConfigHost.get_IsAppConfigHttp()
   at System.Configuration.ClientConfigurationSystem..ctor()
   at System.Configuration.ConfigurationManager.EnsureConfigurationSystem()
   --- End of inner exception stack trace ---
   at System.Configuration.ConfigurationManager.PrepareConfigSystem()
   at System.Configuration.ConfigurationManager.GetSection(String sectionName)
   at System.Configuration.ConfigurationManager.get_AppSettings()
   at log4net.Util.SystemInfo.GetAppSetting(String key)

What have I missed?