After 18 months of trying to get more than 5 hours, and having the battery die on pretty much every journey I make, I sold mine and got the HP Spectre 14. It's easy more powerful (I went for the i7,) same aspect ratio, fine to use as a tablet, Thunderbolt 4 and I get at least 8 hours of proper use. Plus I can replace the battery when it goes.
I'll never go back to surface, even when they advertise 30+ hours, because they simply lie.
Imagine if car manufacturers gave MPG estimates based on the car not moving and the accelerator not being touched!