Allow HTML in a dynamically populated field

I have a Gravity Form with a hidden field that gets filled dynamically. I want to insert a list into the form so I wrote it like this:

<?php gravity_form(9, false, false, false, ['specifications' => 'first key: 1</br>second key: 2']); ?>

But if I fill in and sent this form it doesn’t render the HTML in the email, the same goes for using \n, I only need line breaks so either HTML or \n would be fine

Does anyone have some suggestions on how to handle this?

PS: the list I need to send to the user is of unknown length, with unknown keys and unknown variables so I can’t just create an hidden field for every key and value pair.