For me it's how close the seats are, you have to hold your hands in close to your body to type on a keyboard, and you don't have the room to tilt the screen back for a good viewing angle.
Sometimes I've found resting the laptop in my lap/knees along the screen hinge (so it makes a 45 degree angle with my thigh) to be the most usable. This requires you to pull your shoulders/elbows back however so you usually can't do it if you have someone you don't know sitting next to you.
I have strongly debated bringing my Quest 2 onto a plane and using a wireless keyboard to program with, I think the ergonomics would work out much better when flying coach.
Sometimes I've found resting the laptop in my lap/knees along the screen hinge (so it makes a 45 degree angle with my thigh) to be the most usable. This requires you to pull your shoulders/elbows back however so you usually can't do it if you have someone you don't know sitting next to you.
I have strongly debated bringing my Quest 2 onto a plane and using a wireless keyboard to program with, I think the ergonomics would work out much better when flying coach.