What potential pitfalls or drawbacks may arise from removing session_regenerate_id from PHP code?

Removing session_regenerate_id from PHP code can lead to security vulnerabilities such as session fixation attacks, where an attacker can hijack a user's session. To mitigate this risk, it is important to regenerate the session ID periodically or after certain sensitive actions, such as logging in or changing user permissions.

// Regenerate session ID after successful login
session_start();
if ($login_successful) {
    session_regenerate_id(true);
}