Why is Code Igniter not recommended?

What are the reasons that Code Igniter might not be recommended?

Who said this? To whom? When? Why? For what use-case?

In general, such questions start holywar without any practical output, because they operate with subjective opinions and lacking of facts.

I would say that CI4 is more Microframework, so it cannot be positioned close to Laravel, Symphony, CakePHP or Yii. So when it comes to use-cases, CI4 works best (NB! from my humble opinion, but feel free to disagree or ignore me) for quick prototyping, creating REST APIs, automatic data processing, as middleware (backend-for-frontend type of application) and other similar. Of course, it does not exclude other type of applications.