Why does an almost new laptop battery have 50% remaining charge?

Question

laptops

The laptop did not hold a charge well from the very beginning.
At the time of purchase, Linux did not show even 2 hours on the battery with a full charge, as a rule.
Windows seems to be bigger, it's a pity that I didn't remember it then.
The laptop is about a year old, core i3-7100u (kaby lake), 14 inches, integrated. video, he should not eat a charge. Battery 3-section lithium-ion 42 Wh. Laptop Dell Inspiron 5378, came with ubuntu.
Since I'm sitting under Linux, I was looking for the reason in Linux: D. Tried distributions sometimes, changed configs. As a result, tlp (management of power consumption settings), Mint 19, i915 parameters when loading from Arch Wiki - shows up to 3 hours 50 minutes (when idle, in fact, the browser is running, but there is nothing video, I'm sitting scrolling the page) - this is now, really possible 3 hours to work if there are no large load periods for a long time (you need CPU < 30%).
Windows also, but there the load periodically increases for reasons beyond the control of the user.
It's a lyric, basically.
And the residual battery capacity is approximately 50%. Both Linux and Windows (powercfg energy) and the BIOS diagnostic mode are in solidarity. I wrote the previous paragraphs to the fact that I believe that the battery capacity has always been this way, there is no deterioration in real-time operation.
Either 50% is not true, or the laptop is originally like that. Bios is not calibrated. Once discharged to zero, charged - without effect.
Marriage? Glitch? How many hours do you think such a laptop should work on a battery?

Answer 1

Came to the conclusion that the battery is defective.
Buying a new one solved the problem.

Answer 2

I remember exactly that in utilities for displaying information about battery capacity there should be threshold settings, i.e. the same calibration but only on the software side. Unfortunately, I watched it so long ago that I don’t remember anything, and probably changed a lot.