Something that was really subtle but effective about season 2 was the change in lighting in the sitcom world.
All of season 1 the sitcom world not only uses the filming style of a sitcom but also the hyper saturated color pallet that makes everything bright and cheerful even at night. Even when Neil is attacking Allison. But right at the end, Neil is abruptly slammed into the real world and all the sitcom stylings fall from him.
Then we pick up season 2 and we still have the multicam shots of sitcom world, the lighting is still brighter than the real world, but it’s subtly desaturated by comparison to season 1. Neil was the third person to be awakened to Kevin’s abuse, but he was always the most loyal so he tries to write it off but he can’t. Allison and Patty are constant reminders of what happened, and as he falls apart it becomes more and more difficult for him to ignore or excuse Kevin’s abuse. The awareness subtly eats away at him.
As more people become aware of Kevin’s behavior, it weakens the sitcom world. Slowly, the color is drained too.