Switching to Child Theme Deletes Custom "Additional CSS"

Hello,

I'd reviewed this page under the section, "Will I lose my changes when I add a child theme?"
https://docs.generatepress.com/article/using-child-theme/

For me, when activating the child theme (based on your GP starter) I'd also lost the custom Additional CSS I'd added via the Customizer.

Perhaps I didn't understand the statement, "If you’ve only used the theme options in the Customizer, you won’t lose any of your changes." but to me, I'd suggest adding a note about backing up any custom "Additional CSS" too :)