When you draw with the Pen extension, certain color values are rendered one shade too dark. This projects demonstrates that by drawing all 256 shades and highlighting those that are too dark. Click a highlighted dot to see the expected and actual color values for that dot. Click the colors on the right side to switch between them. As you can see, the anomalies aren't color specific.
The anomalies were discovered by @mlcreater: https://scratch.mit.edu/projects/824609626/#comments-335902299 https://scratch.mit.edu/projects/824609626/#comments-343307610