This functionality is available for PRO version.

Name: wp-hide/ob_start_callback/text_preserve
Type: Filter
Arguments: $buffer

This filter can be used to change any outputted HTML buffer. Similar to wp-hide/ob_start_callback except this will run inside text preserve loop.

        add_filter( 'wp-hide/ob_start_callback/text_preserve', 'custom_ob_start_callback_text_preserve' ); 
        function custom_ob_start_callback_text_preserve( $buffer )
            {
                
                $buffer =   str_replace("Powered by WordPress" , "", $buffer);
                
                return $buffer;
                   
            }

The $buffer contain the full HTML data which is being sent to browser as server response.