This disk is in the Old Town.
You can get it when you return a second time, just after getting the Havok Glove.
The ice cream vendor wants you to get rid of rubble and 4 Sargeant ants.
After you kill the first one, there are two more behind. Kill these two and on the left is a fenced area. Enter this and there’s is a havok symbol. Enter/go underground and complete the puzzle - your reward is this VR disk.