Use a hyphen instead of a backslash as the pipe name/identifier separator

src/OpenIddict.Client.SystemIntegration/OpenIddictClientSystemIntegrationPipeListener.cs

@@ -140,7 +140,7 @@ public sealed class OpenIddictClientSystemIntegrationPipeListener : BackgroundSe
 #else
                 NamedPipeServerStreamConstructors.New(
 #endif
-                    pipeName                  : $@"{options.PipeName}\{options.InstanceIdentifier}",
+                    pipeName                  : $@"{options.PipeName}-{options.InstanceIdentifier}",
                     direction                 : PipeDirection.In,
                     maxNumberOfServerInstances: NamedPipeServerStream.MaxAllowedServerInstances,
                     transmissionMode          : PipeTransmissionMode.Byte,
@@ -151,7 +151,7 @@ public sealed class OpenIddictClientSystemIntegrationPipeListener : BackgroundSe
                     inheritability            : HandleInheritability.None,
                     additionalAccessRights    : default) :
                 new NamedPipeServerStream(
-                    pipeName                  : $@"{options.PipeName}\{options.InstanceIdentifier}",
+                    pipeName                  : $@"{options.PipeName}-{options.InstanceIdentifier}",
                     direction                 : PipeDirection.In,
                     maxNumberOfServerInstances: NamedPipeServerStream.MaxAllowedServerInstances,
                     transmissionMode          : PipeTransmissionMode.Byte,

src/OpenIddict.Client.SystemIntegration/OpenIddictClientSystemIntegrationService.cs

@@ -202,7 +202,7 @@ public sealed class OpenIddictClientSystemIntegrationService
         using var writer = new BinaryWriter(buffer);
         using var stream = new NamedPipeClientStream(
             serverName        : ".",
-            pipeName          : $@"{_options.CurrentValue.PipeName}\{identifier}",
+            pipeName          : $@"{_options.CurrentValue.PipeName}-{identifier}",
             direction         : PipeDirection.Out,
             options           : PipeOptions.Asynchronous,
             impersonationLevel: TokenImpersonationLevel.None,