Overview
In the following article, I performed content registration using Python with Basic authentication.
This time, I tried API Key Authentication, referring to the following article.
https://designkojo.com/post-drupal-using-jsonapi-vuejs-front-end
API Key Authentication
The following module was used.
https://www.drupal.org/project/key_auth
A “Key authentication” tab appeared on the user edit screen, allowing an API key to be generated.

When using the API key, the following program can be used.
Notes on Multilingual Support
As a note, it appears that creating translation data is not supported.
https://www.drupal.org/docs/core-modules-and-themes/core-modules/jsonapi-module/translations
While updating existing translation data is possible, the following error occurred for nodes without translation data.
A workaround for this issue may already be available. I plan to continue investigating.
Summary
I hope this serves as a useful reference for using Drupal’s JSON:API.