Sounds like the classic ADD/OCD thing.
I don't watch tv anymore, like at all. Occasionally I'll sit down with my parents and enjoy some move or random show they're into, but I too struggle with staying focused. But it's mostly cause I'm tired, bored, or itching to do something "productive" - like aimless drawing, lol. I guess I'm just overexposed to tv/streaming stuff and I'm subconsciously want to stimulate myself in other ways? Doesn't help that I'm OCD and feel obligated to produce a few pages of a comic every week (though deadlines are helpful, cuz I'm lazy otherwise)
Guess it's just a part of growing up, and our time/focus-demanding society/responsibilities.
Maybe try allowing yourself to relax your mind a bit? It might take some practice and work, but the brain can be trained to calmly focus on command, mostly...Just have the intention to watch a show without any judging thoughts, observe, and find something enjoyable about it. Enjoy turning the brain off, if you can.