@dickraney For now, my workaround is to put a dark box around it, by switching to the Text editor (HTML) for the emails, and using this code:
<div style="background: #555; padding: 1em;">{{cart.unsubscribe}}</div>
It’s not looking great in the email, so I’m hoping there’ll be a real fix for this issue soon, but at least the link is more visible this way.