Unsupported content with the new editor

Summary

Pasting specific contents on new pages created with the new editor (blog posts/ meeting notes) can cause a Unsupported content error.

Environment

• Confluence Cloud

Steps to Reproduce

1. Create a Blog post
2. Copy some content from external sources i.e. Google Spreadsheets and insert into the page;
3. Publish it.

Expected Results

The blog post/page should render correctly.

Actual Results

A "Unsupported content" box is shown instead of the page's content as shown below:

Workaround

Remove the content from external sources.