It's more of a reference, but some Tarot graffiti, if you don't scan them, but approach, sometimes a "Whoah" dialogue option appears. Which was Tom's reaction when Morphius jumped across the buildings, still a Keanu Reeves related meme. A Matrix 1 reference.
Another one, that I don't think counts as an Easter egg, but still very cool and cyberpunk related, is the sentient SCSM machine is voiced by Bryan Dechart (voice actor of Connor from "Detroit: Become Human"). With a last name like that the guy is destined to play sentient beings in cyberpunk entertainment pieces.
Also, the most expensive car in the game - Aerondight. It's a sword in TW2 and TW3. In the latter given to Geralt if he completes a "There Can Be Only One" quest. The name of that quest is another reference for 30+ people.
The writers are very good