There's no work community or camaraderie at home. Doggo should count. Kittah jumping on the keyboard is just using you for food and grooming.
There's no grabbing lunches.
There's no visiting X down the hall.
No grabbing a beer after work.
Boss G, H, or J can't see you around.
Colleagues M, N, P, and Q don't have a sense of your performance or amount of work that happens far away. "Out of sight, ..."
Pair programming becomes less effective.
It's typing away by yourself like a writer, occasionally seeing "holograms" of other people on screens, or taking calls like you're working a call center.