CI3 to CI4 Migrations (__construct)

You can definitely use the constructor for almost anything you need to. It was purposefully left blank so framework code didn't get in the way of what you needed.

However, redirects no longer work from within constructors. Instead, you should look at controller filters for permission checks and the like.

If I am right understanding the Controller Filters starting working before apps controllers and check url's or form action type as hooks in CI3 ?