The nullable annotation on JwtSecurityToken is unnecessary here since ReadJwtToken will throw an exception if the JWT is invalid, not return null. The nullable annotation should be removed for clarity.

The async void event handler lacks error handling. If LoginWithBrowserAsync throws an exception, it will crash the application since async void methods cannot propagate exceptions. Add a try-catch block to handle potential exceptions and display an error message to the user or log the error appropriately.

Triggering the login flow automatically when the window loads may not be the desired behavior. This prevents users from seeing the UI or understanding what's happening before authentication begins. Consider whether this automatic trigger is intentional or if users should have the option to manually initiate the login by clicking the "Retry Login" button first.

Using instance-level fields for PKCE state and code_verifier creates a potential security issue if multiple login attempts occur concurrently. If a second login is initiated before the first completes, the state and code_verifier values will be overwritten, causing the first login attempt to fail validation. Consider using a dictionary keyed by state to support concurrent login attempts, or add proper locking to prevent concurrent logins.

Deserializing without null checking could throw a NullReferenceException if the response content is valid JSON but the deserialization returns null. Consider adding a null check after deserialization before accessing properties with the null-forgiving operator.

The success log message that was previously displayed after successful browser authentication has been removed. This means users will no longer receive visual confirmation in the logs that their login was successful. Consider adding this feedback back, or ensure that success is communicated to users through another means (such as a UI notification or status update).

The Loaded event handler is subscribed but never unsubscribed, which can cause a memory leak. The event handler should be unsubscribed when the window is closed or disposed. Consider unsubscribing in an overridden OnUnloaded method or by using weak event patterns.

The RestClient is now created without specifying a base URL, which will cause the feedback API requests to fail. The RestRequest uses relative paths like "/api/feedback/anonymous" and "/api/feedback" which require a base URL. The original code correctly specified "https://cloud.one-ware.com" as the base URL. This should be restored or obtained from settings using GetRestClient().