Concrete 9.0 RC3 - Image thumbnail not displaying on page

After the update my images are no longer displayed. I have the attribute field still visible in the composer, but the image does not print in the page anymore. Here is my code:
Screenshot 2021-09-02 at 16.53.53

@oximasarl One thing that changed with v9 is when instantiating a class using Core::make or $app->make: if you’re providing an array of parameters you now have to use array keys based on the parameters variable names.

In this case the ‘html/image’ class uses $f as variable name for the file parameter so that one line should be changed to:

$img = Core::make('html/image', array('f' => $thumbnail));