Microsoft hides file extensions in Windows by default even though it's a security risk that is commonly abused by phishing emails and malware distributors to trick people into opening malicious files.

Microsoft has added a feature on the File Explorer Options or Folder Options ribbon and a Windows mini window, allowing the user to enable or disable the file extensions’ visibility in the File ...

You know when you go to folder options, there's an option to choose whether you want to hide file extension for known file types?