Honestly, I was also surprised. Meanwhile I found out, that it’s most probably not a Duplicati issue, but some weird Adobe issue. There are more apps maintaining a connection to activate.adobe.com.
I have the suspicion, that on this computer the Adobe Connect conferencing stuff is installed.
@nescafe yes, that would make perfekt sense. Sinkholing the adobe activation, and then Duplicati listening only to the loopback interface, making it apear to have a connection to it.