I was able to verify that this is a new bug that was introduced between .NET 10 Preview 5 and Preview 6 I have a build of my app from July 7th which is using .NET 10 Preview 5 and it does not exhibit ...

Following the steps: Create a winforms .NET Core project Add a Button control with a background image Enable DarkMode by Application.SetColorMode (SystemColorMode.Dark) in Program.cs file. Build & run ...