Thank you @mustafaabuq
That explains it.
Step titles are very important.
Your step that’s actually formatting the text data is currently titled node:
However, your Notion - Create Page step is expecting that step to be named formatter:
That’s why you’re seeing an error.
How to fix
First rename the node step to formatter, then click Test to regenerate the exported data.
In the Exports tab, you should see steps.formatter.$return_value in the results.
Then, test your Notion - Create Page step again, this time it should be able to import the data from the formatter step.