The code that was released wasn't how the websites looks and feels. The code that was released was for the website's algorithm, the way it presents you information from who/what. Substack was trying to copy how the website looks to create their own "fork" of Twitter. They would need to make their own algorithm when it comes to serving content, but the "heart" or more like "body" of Twitter was what they were allegedly downloading. So Elon Musk banned Substacks IP, which in turn gave people that warning message when clicking on a Substack link on Twitter, saying the link might be dangerous.
The code that was released wasn't how the websites looks and feels. The code that was released was for the website's algorithm, the way it presents you information from who/what. Substack was trying to copy how the website looks to create their own "fork" of Twitter. They would need to make their own algorithm when it comes to serving content, but the "heart" or more like "body" of Twitter was what they were allegedly downloading. So Elon Musk banned Substacks IP, which in turn gave people that warning message when clicking on a Substack link on Twitter, saying the link might be dangerous.