I'm a Witcher 3 obsessive, revisiting CD Project's opus once every two or three years, but that barely holds a candle to the Witcher 3 devotion of xLetalis, a YouTuber who's been documenting the massive game's secrets and esoterica since release, and is still finding new surprises to this day.
The latest, as reported by IGN, is an easter egg that seems to have been intended for plucky boundary breakers who managed to find themselves outside the normal play area in Novigrad. Underneath the metropolis, you can encounter an Uncle Sam-esque drawing of a Temarian soldier pointing at the viewer, with text underneath reading "CDPR Needs You."
XLetalis was informed of the easter egg by a viewer who claims to have glitched into the space under Novigrad—xLetalis himself was unable to replicate this, and managed to reach the drawing via a console command. The YouTuber was unable to find another instance of the art in The Witcher 3, but recalled seeing something similar elsewhere in the game. My guess? He may have been thinking of a similar riff on old US recruitment posters found around The Witcher 1's Vizima all the way back in 2007.
XLetalis wondered if this might have been a genuine stab at a recruitment tool by CD Projekt, and I think there is a genuine possibility there. If you were able to break out of bounds and see this message, that speaks to having the right stuff to become a quality assurance tester. My guess is that this was placed as a cheeky response to a known shippable bug that let you get under Novigrad, similar to the one xLetalis' viewer used, if not the exact same one.
You may recognize xLetalis' name from our previous reporting on a Witcher 3 secret that only shows up after seven in-game years pass, or the cross-game ARG/easter egg FF:06:B5, found in both Cyberpunk 2077 and The Witcher 3. XLetalis periodically releases compendiums of Witcher 3 secrets, like this one from a few months ago. My favorite relates to Blood and Wine's Cianfanelli Bank: not only can you get banned for life if you mess up its associated quest, but the staff will also put up a "do not serve this man" sketch of Geralt in the lobby. Ouch.