I also saw that every point in the universe is the center. So what does it mean that the universe is expanding? It depends on the repository?
The expansion of the universe does not apply to bound systems. It applies only to very large unbound structures such as galaxy superclusters.
I think, as far as I understand it, the expansion of the universe is overshadowed by other factors at smaller scales.
The gravity between the earth and the sun is strong enough that even as the universe expands, the distance between the earth and the sun is not affected.
Gravity continues to affect structure more than the expansion of the universe until you get to the largest scales, the distances between galactic clusters. At that scale, on average, everything is moving away from everything else because the universe is expanding and the distances involved are so great that gravity is not strong enough to keep it all together.