I have a Surface laptop 5 as well. The battery life is atrociously bad. 4 hours is an accurate estimate as to how long I can expect the battery to last as well. Keep in mind it was like this from the first day I bought it with 0 software installed on it. I only use this laptop for basic functions the majority of the time email, Word etc...
I have also tried al of the suggestions Microsoft says but it makes no difference. There is no way this laptop will ever get anything near 17hrs even doing nothing on it!! I would be ecstatic getting half of that.
It is a shame because otherwise it is a nice laptop.