The concept you're referring to is known as the "observable universe" and the discrepancy arises due to the expansion of space.
The universe is estimated to be around 13.8 billion years old based on the measurements of the cosmic microwave background radiation, which is the remnant radiation from the early universe. However, since the universe has been expanding over time, the light emitted from distant objects has also been traveling through expanding space.
As space expands, it stretches the wavelengths of light traveling through it, causing a phenomenon called cosmological redshift. This means that the light waves get "stretched" to longer wavelengths, shifting them towards the red end of the electromagnetic spectrum. The amount of redshift is directly related to the expansion of space.
The expansion of space has been ongoing for billions of years, allowing light from extremely distant sources to reach us. The light that we observe from objects that are currently about 46 billion light-years away started its journey toward us when the universe was much younger, but it has taken a long time to reach us due to the stretching of space.
It's important to note that the 46 billion light-year figure is a comoving distance, which takes into account the expansion of space over time. It doesn't mean that those objects are physically located 46 billion light-years away from us now. They were much closer when they emitted the light we observe today, but the expansion of the universe has stretched the space between us and them.
Detecting light from objects that are farther away allows scientists to study the early stages of the universe's evolution and provides valuable insights into its history and properties.