[mirrorlake]

My armchair hypothesis is that using your phone, internet, or TV lacks sensory novelty--you frequently sit in the same place, doing the same thing.

It's a repeated stimuli, which causes your brain to filter a lot of it and discard it, leading to the feeling like a night watching TV was a night doing nothing. Your memory of watching TV blends with all memories of you watching TV, especially after a few days have passed.

You have to switch up your routine and do something new or otherwise different, and you will retain a memory of that event much more clearly and it will feel like you "did something".

My most clear memory of a night in the past week was game night where we played a physical card game. I don't remember any individual night where we watched TV.

[onesafari]

That makes sense and could explain a lot of it. The time spent is essentially compressed in memory making it seem smaller than it is.