The inclusion of the word "free" in the prompt is a hook. It suggests that the service is usually paid but is being offered to you for free. In the context of "Google Apps Script," this is a lie. Legitimate Google Apps Script developers do not monetize their scripts via "watermark removal fees."
Any website or YouTube video claiming to offer a “free one-click removal hack” is either lying or trying to infect your computer.
OAuth verification is not required for Google Apps Script projects "whose owner and users belong to the same domain or Google Workspace organization". This means if everyone using your script is within the same Google Workspace account, you won't see the warning regardless of verification status.