The Include responses option only adds respondents’ actual answers to the thank-you email. Since the Presentation Text question is meant only to display information and does not capture responses, it is not included. As a workaround, you can add a Single Select question right after the Presentation Text, provide a single option set as the default, mark it as hidden in the settings, and copy the same text into it. This ensures that the text from the Presentation Text question also appears in the thank-you email.
Screenshot for reference.
Here are some guides for reference:
Hidden Question
Default Selection
Multi-Choice Select one