under my char there's the pattern, above is pristine terrain
![Image](https://forums.factorio.com/images/ext/12c314ef0f5d657625aa7a65bd512c68.jpg)
although rseding already stated it is intended behavious, it's quite easy to reproduce.Loewchen wrote:This behaviour is very old but we never could reproduce it.
Can you provide a save with: Normal surface > placing concrete > removing concrete > abnormal surface?