Compatibility with DropzoneJS

The easiest fix would be to implement the form_alter with the new ID and call the old form_alter...

function focal_point_form_media_library_add_form_dropzonejs_alter(array &$form, FormStateInterface $form_state) {
  focal_point_form_media_library_add_form_upload_alter($form, $form_state);
}

But this feels wrong, having some hook of a random contrib module. Is this the way to go?

Having a hook that alters the media_library_add_form_dropzonejs form is not really any different than altering the media_library_add_form_upload form. I just did it this way in order to not repeat code.

Perhaps it would look less weird if it was changed to a hook_form_alter() with a condition to check the form ids inside the function.

This works for me using focal_point 2.0.

Am seeing this issue with focal_point 2.0.2

Putting the suggestion from #2 in to a custom module resolves the issue for me as a workaround until fixed properly.
e.g.

function MODULE_NAME_form_media_library_add_form_dropzonejs_alter(array &$form, \Drupal\Core\Form\FormStateInterface $form_state) {
  focal_point_form_media_library_add_form_upload_alter($form, $form_state);
}