Remove This Application Was Created By A Google Apps Script User -

The most common way to "mask" the Apps Script environment is to embed your Google Apps Script URL into your own personal or business website.

Because the web app is hosted on the ://google.com domain, Google injects this iframe header as a security measure to prevent phishing and spoofing. Even with a Google Workspace (formerly G Suite) Business or Enterprise account, the banner remains. The most common way to "mask" the Apps

If you want to completely strip the banner, you cannot host the app on Google’s servers directly. Instead, you can use a "proxy" or a middle-man server. If you want to completely strip the banner,

While Google includes this for security and transparency—to ensure users know they aren't interacting with an official Google product—it can be a major eyesore for developers trying to create a professional, branded experience. the banner remains.