Error on creating Page content in Notion

Good day folks, I have a scenario which:

  1. Gmail - when an email is tagged as “To-Do”, it sends its content to ChatGPT
  2. ChatGPT - then analyzes the contents and gives me a summary, possible to-dos and lists all attachments
  3. Notion - a new database entry is created in my To-Do database, using information (title, sendee, company etc.) from the Gmail
  4. Notion - then in the newly created database entry’s page, 5. I want to insert a block of text - output from ChatGPT in step 2.

Issue
I tried using a Notion module (Update a Page Content) in the 4th step, but I got this error:

Updating a page via the blocks endpoint unsupported. Call patch /v1/pages/:page_id instead

So ChatGPT suggested I used HTTP request instead, but however I try, I am not getting results (the Notion Page body does not get updated, no text included). I am using HTTP module with these parameters:

And this is the overview of HTTP (in the details, it says “Error 400”