In the latest Developer Survey email from Stack Overflow, sent Jan 24, 2019, both the email preference links at the bottom result in "Invalid Request". "Leave Feedback" works as expected. I was able to reproduce this on Android (Gmail app) and on a desktop. Please see the images below. I'm not sure how to check if this is just me or universal.
Alex, we made a mistake when we were setting up our email campaign, and we sincerely apologize. The issue affected a few dozen people, including yourself.
We are unsubscribing you (and others affected) on the backend, so you won't receive additional emails like this unless you explicitly opt in at a later date.
Thank you for your patience.