Why urine color gets yellowish? does this scientific or natural issue?

The 'darker' it is usually means you aren't drinking enough water .................

It just usually means you arent drinking enough water or clear liquids.

Other reasons are maybe you've started to consume more fiber than usual which can make your urine come out more yellowish than usual. New supplements or pills can also be the cause.

It means you can't write a grammatically correct question.

Your urine carries lots of things that your body no longer needs, things like sugar for instance. If you are dehydrated, you will pass less water containing the same amount of rejected waste. As there is less water, the urine appears like a yellow to even a dark brown colour because it is stronger. Drink more water.

Usually a food issue. And hydration levels.