Getting HTTP 404 when redirecting but reloading works.

Using CodeIgniter 4.5.3, after doing user identification (you know, creating a session variable and updating the database to register the login) I do a redirection to the index page this way:

PHP Code:

return redirect ()->to ('', 307); 


It always returns a HTTP 404 error, but reloading the page (i.e. [Ctrl]+[R]) loads it without any error.  Log doesn't show any message.

Accessing the index page directly (by putting the URL) doesn't fail.

Doing other redirections (for example, when the index page detects the user isn't identified it redirects to the login page using same code) works without any problem.

Anybody knows any reason for this behavior?