Same her on others saying they have seen them before. This one is new for me, it is from the b16294.1 'S' sku Spoiler
I think that I might have mentioned to you before that Spotlight images come from Bing through the Content Delivery app. At this point in time, the Spotlight images are not determined by which build/sku you use. New images do appear from time to time, but they are from Bing.
Wzor himself is shady. Behaves like some master of Warez. As long as those scripts pull files from Microsoft servers, no harm.
I've had 10.0.16294.1 installed for about six hours, and got an "Update for Windows 10 Version 1709 for x64-based Systems (KB4041994)" within the past hour or so. No reboot was required. Can't find anything about KB4041994 on Microsoft's site... Spoiler
Interesting... They could be testing the windows update function of this build which could strongly suggest this is indeed a release candidate (not necessarily RTM). It could also be the rare instance to patch a zero day exploit, but I think I recall only recall 3 of those in the history of the insider preview program.