Earlier this month, Google started tracking a new issue in which source URLs for files in Google Drive aren’t working when they’re embedded, such as in Nintex Forms, emails, and web pages. This issue can impact any Nintex product expected to host an image, and seems to affect many (possibly all) file types. This issue has been acknowledged by Google on their Issue Tracker

This conversation in GitHub demonstrates a workaround with a new URL format. However, this workaround ultimately requires the URL to be updated anywhere it’s been used.

I’ve written a Knowledge Base article about it here regarding Nintex Automation Cloud.