I've heard a lot about the age of the universe being 13.8 billion years old.
Is it really true?

The universe is 13.8 billion years old... how did you calculate.

The rate of expansion of the universe is determined by the Hubble constant. The Hubble constant represents the rate of retreat per million parsecs (3.26 million light-years) away from Earth. Using this Hubble constant, we can calculate the time it takes for the universe to expand to its present size. If we take the reciprocal of the Hubble constant, that is the age of the universe, called the Hubble time. When the Hubble constant is 50, the universe is about 20 billion years old, and when it is 100, the universe is about 10 billion years old.
In March 2013, the Hubble constant obtained from data obtained by the European Space Agency's Planck satellite from precise cosmic background radiation observations was about 67.80 km/s/Mpc. Recalculating this value, the age of the universe is 137.98±0.37 billion years, which is a value with an accuracy of only 0.268% error. So let's simply remember the age of the universe as 13.8 billion years.

67.80...
Because of this value, the age of the universe is said to be 13.8 billion years.
It is said that this value is gradually increasing.
It is not a fixed value, but while reducing the measurement error
And as science advances, it is getting more and more expensive.
So, it seems that the age of the universe is a little younger than we think.
There is no big difference between 10 billion years old and 13.8 billion years old haha

[Chul-Woo Oh's Science Forest] Expansion of the universe, the age of the universe - The Hankyoreh

When you are covering the field of cosmology, this tension is rather interesting. The change in the age of the universe experienced by a science reporter is not embarrassing, but natural, considering the structure of the universe that can never know the end, and the time in the universe that humans who live at most 100 years old cannot imagine. In the universe, where 95% of dark energy and dark matter, which science has yet to reveal, these changes and modifications seem to be the force that pulls us out of the chaotic reality and draws us into the imagination of the wonders of nature. Cosmology is open to change, and therefore fascinating.

In this infinite universe, isn't it only humans who are curious about the universe...
What will the universe be like after humans disappear?