Episode 4 is the most beautiful depiction I've seen on TV of surviving trauma and mental health issues - specifically suicidal thoughts.
When Billy speaks to Max, he makes it clear that the survivor's guilt has led Max to want to die at times, to "follow" Billy into death. Her favorite song also alludes to this as well: "And if I only could, I'd make a deal with God, and I'd get him to swap our places." She wishes that she had died instead of Billy.
The visions that the victims see of their trauma are very similar to PTSD flashbacks. Vecna himself then speaks to them, unlike the monsters in any previous season. His voice is essentially their inner thoughts taunting them. For example, asking Max if she "would like to join" the dead victims is a representation of Max's own suicidal thoughts. It's worth noting too that Chrissy's struggle was with an eating disorder, which have high rates of suicide.
When the opening to the outside world appears, it is far away from Max and Vecna. She can see her friends and hear them calling for her from a distance. But Vecna tells her "they can't help you." This hits close to home for those who've struggled with mental health. You can see the outside world, you may know people care about you, but it all seems so far away. Your brain tries to convince you that nobody can help you. You are trapped in your own mind fighting a battle they can't see.
Max tries to fight back by saying "You're not really here." Anyone with mental illness can relate to this - trying to push back against your own mind, knowing it is not representative of reality. But Vecna replies, "Oh, but I am, Max." - showing how even if these things are just products of our mind, they're still very real to the person experiencing them.
The most heartbreaking moment for me is when Vecna extends his claw, closing in closer and closer to Max's head. We know this is the last thing that happened before the others died. There is a look of panic on her face, and to me this doesn't read just as a fear of dying. In her eyes I see the struggle between wanting to die, to succumb to her demons, and wanting to fight back. In the context of Vecna representing her suicidal ideation, she is at her rock bottom, seconds from death.
But she looks back at the opening. Fighting through her pain, she remembers the happy memories with her friends. Her face during this part is still one of great struggle. Part of her wants to die and another part is trying desperately to get the strength to hold on. She is not just fighting for her life, but fighting to want to be alive.
Then, in a split-second, she slices Vecna's neck. She makes the decision to fight, to live. And she takes all her bravery, all her strength, and sprints towards the opening. It's not enough just to decide to live, you then need to claw your way back out of the hole. This part of the scene is nearly a minute long. The road to recovery from mental health struggles is not quick, or easy. The facial expressions as she is making this last-ditch effort to save her own life I can't even put into words, but I can feel it. She runs with everything in her, panicked but determined, falling down and getting back up, covered in mud, the world crumbling around her. But she keeps running. Damn if that's not beautiful, I don't know what is.
[Image Description: Screenshots from Stranger Things Season 4, Episode 4.
1-3: Billy says to Max, "And why, late at night, you have sometimes wished to follow me. Follow me into death."
4-5: Max sees Vecna's victims' corpses tied up with tendrils. Vecna says, "Would you like to join them?"
6: Vecna looks over his shoulder as Dustin yells, "Come on, Max." Vecna says, "They can't help you, Max."
7-8: Max says, "You're not really here." Vecna replies, "Oh, but I am, Max."
9: Vecna's claw surrounds Max's head, terror in her eyes.
10: Max sprints towards the opening to the outside world, rocks crashing behind her.]