Object of type CodeIgniter\Session\Session is not callable

Your PHP is defective.
The Session class has never been Invokable. This means that your code could not work in principle.

???

print view('my view', ['session' => session()]);


myview.php
...
<p><?= $session->xyz ?></p>
...

So the proper way to access session data in a CI view is to use the session() function or fetch the session data into another variable and pass that to the view? I don't see why it matters. This has been working in CI4 for many years.

Simpler is always better