debianize-mobilizon/lib/web/templates/email/activity/_group_activity_item.text.eex

<%= case @activity.subject do %><% :group_created -> %><%= dgettext("activity", "%{profile} created the group %{group}.", 
    %{
        profile: Mobilizon.Actors.Actor.display_name_and_username(@activity.author),
        group: @activity.subject_params["group_name"]
    }
) %>
<%= ~p"/@#{@activity.subject_params["group_federated_username"]}" |> url() |> URI.decode() %><% :group_updated -> %><%= dgettext("activity", "%{profile} updated the group %{group}.", 
    %{
        profile: Mobilizon.Actors.Actor.display_name_and_username(@activity.author),
        group: @activity.subject_params["group_name"]
    }
) %>
<%= ~p"/@#{@activity.subject_params["group_federated_username"]}" |> url() |> URI.decode() %><% end %>