While the lab massacre unfolds in memories, the present-day Hawkins crew discovers the "Water Gate" at the bottom of Lovers Lake.
Vecna uses Nancy to reveal his backstory, showing her the Creel House and confirming he has been the puppet master since 1979. Why It Matters [S4E7] Chapter Seven: The Massacre At Hawkins Lab
Eleven doesn't just defeat Henry; she rips a hole in reality. While the lab massacre unfolds in memories, the
out of self-defense, not curiosity.