Other people told me didn’t know it too, but here’s the thing.
I tried not to fool myself by looking at the map while walking around and say: THAT’S the same.
Here is what I did.
I saw the update page and i thought: “Wolfenstein ET!”
Then I looked at the screenies and tried to recall the maps lay-out without playing the tf2 version. For instance: The screenie with ammo/health cabinet in the middle of a tomb-like hall with torches is what I recognized as the first spawn. Then I recalled I could walk left and right(symmetrical) and face a spawndoor with hyroglyphs that slowly slides down when the game starts. Well, since I recalled this before actually playing the tf2 version, there is just no way I could have looked at the spawndoors in the game and THEN try to fit that in my memory.
The same goes for tons of specific features in the map. Such as the control point in the background image. I could recall that you can walk left there (down a bit) and then go left and right. To the left would be a sandy hollow tunnel and to the right a hallway. These things I recalled couldn’t be spotted in any of the tf2 screenshots and are not coming from any material released in the update, yet they matched the reality when checking the map afterwards 
The only thing I can imagine is that I could be mixing up games, but the egypt theme and excavation thingy is really an ET thing. I immediately thought of ET and I mostly played ET as online shooter (apart from halo ce ages ago, no custom maps played, and aa with some schoolfriends, no custom maps there either). So if i’m not going nuts or psychic ( 
) I’m 99,99999% sure this map is from the ET mappers community.
(BTW: it’s the lay-out of the map that striked me first, the egypt thingie was more secondary and complementary to the map I know.)
) I’m 99,99999% sure this map is from the ET mappers community.