On page 251, when creating the form components for the admin dashboard, this example code:

<.form
  for={:gender_filter}
  phx-change="gender_filter"
  phx-target={@myself}
  id="gender-form"
>

Produces the following deprecation warning:

warning: Passing an atom to "for" in the form component is deprecated.                                                                
Instead of:

    <.form :let={f} for={:gender_filter} ...>                                                       

You might do:

    <.form :let={f} for={%{}} as={:gender_filter} ...>

Or, if you prefer, use to_form to create a form in your LiveView:
                                                                   
    assign(socket, form: to_form(%{}, as: :gender_filter))

and then use it in your templates (no :let required):

    <.form for={@form}>

The helpful error message explains a couple possible fixes. I went for the easy one:

<.form
  for={%{}}
  as={:gender_filter}
  phx-change="gender-filter"
  phx-target={@myself}
  id="gender-form"
>