The set logo is the Wikimedia logo which violates point 7 of the terms of use namely, "Do not confuse users by using Wikimedia logos on web pages."
If you try to replace the logo with a screenshot from the original phabricator logo or something other, there is this problem:
The instance still uses a logo from wikimedia. I don't know how I can change this because, I guess, this logo is set by a custom CSS file?
If I change this file, I guess puppet will overwrite it. Is there a solution for this problem?