MDN URL: https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs

What information was incorrect, unhelpful, or incomplete?

The Hello World example incorrectly refers to the "comma" character as a "quote" character. The percent-encoding of %2C corresponds to the "," character, not the "'" character

Specific section or headline?

This is in the "Syntax" section under the "data:,Hello%2C%20World!" example

What did you expect to see?

The word "quote" should be replaced with the word "comma"

Did you test this? If so, how?

This is simply a typo based on the standard of percent-encodings