[Dark Mode] The BackColor of the ProgressBar control should not be changed

.NET version

9.0.100-rc.1.24418.2 + build private dll from winforms repo main branch

Did it work in .NET Framework?

No

Did it work in any of the earlier releases of .NET Core or .NET 5+?

This is a new feature Dark Mode: https://github.com/dotnet/winforms/pull/11857

Issue description

In Dark Mode, the BackColor of the ProgressBar control will change to red when its BackColor property is set to red The BackColor of the ProgressBar will not be changed in Classic Mode

Dark Mode

Classic Mode

Steps to reproduce

1. Create a WinForms .NET Core application with ProgressBar control
2. Enable DarkMode by Application.SetColorMode(SystemColorMode.Dark) in Program.cs file
3. Set the BackColor property of the ProgressBar to red
4. Run the application