Our current payments.wiki unsubscribe link (the one from the footer of the Civi Thank You Email Receipt) passes the email address through the URL.
https://payments.wikimedia.org/index.php/Special:FundraiserUnsubscribe?p=thankyou&c=-1&e=REDACTEDEMAIL%40wikimedia.org&h=02caeab092166045c04a3e68231cb72f15951336&uselang=en
According to Trilogy, it's best practice to not pass email address through the URL because of GDPR. In addition, our unsubscribes between fundraising campaigns seem to be pretty substantial and our theory is that it's because of that link.
We'd like to request an edit to the unsubscribe form so that the donor enters their email address in a text box instead of the link auto-populating it.