Cannot download with the "Download my painting" button; CSP error: “blocked the loading of a resource at data:image/png;base64”

### MDN URL

https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements/a#using_the_download_attribute_to_save_a_canvas_as_a_png

### What specific section or headline is this issue about?

_No response_

### What information was incorrect, unhelpful, or incomplete?

When you click the "Download my painting" button on the example canvas, it doesn't download the painting.

### What did you expect to see?

I expected to download a png file of the canvas.

### Do you have any supporting links, references, or citations?

_No response_

### Do you have anything more you want to share?

In the console it keeps printing this error: `Content Security Policy: The page’s settings blocked the loading of a resource at data:image/png;base64,[insert some base64]... ("frame-src")` when I click the download button.