2.7.9 version issue on Gutenberg editor

When we create multi-step forms and try to use them on some pages through the Gutenberg page editor, we cannot save the page.

Instead, we get the following error:
“Updating failed. The response is not a valid JSON response.”

If we remove the Multi Step for Contact Form 7 plugin or roll back to version 2.7.8, the page saves without issues. Even simple forms are not allowing us to save with the latest version.

Please take a look and fix this issue in the latest version.