Yes, you've read the title right. It does say the universe might be "thinner" than we had previously predicted. It means the galaxies, gas, dark matter, etc. might not be clumping together as much as predicted by the standard model of cosmology. It's possible that the results are due to chance, and they're not real. It's also possible that the LambdaCDM model is not as accurate as we thought it was, or the universe has another hidden dark component that we are not aware of yet.
The Kilo-Degree Survey (KiDS-1000) observed about 31 million galaxies over seven years and used the data to map the distributions of dark matter and other hidden gas in the universe using a technique that used gravitational lensing. Even though we can't see dark matter or other hidden gas directly, their gravitational pulls cause the light coming from distant galaxies to get distorted. These distortions can be measured to map the distributions. You can learn more about gravitational lensing here.
The results show that the clumping of the universe's various components is about 10% "thinner" than predicted. This is not the first indication that the universe might be thinner than expected as the first hint came in 2015. Several different surveys since then have indicated similar results.
More details coming soon...