The universe does not expand. Matter is the new reality since 13.8 billion years ago, and it is expanding. Yet energy, space and time were already present before matter derived. It would be weird to say otherwise. We only have data about the beginning moment for matter. We do not have data that time, space or energy had their beginning then and there as well.

The Big Bang model is to blame, or better, the human brain is to blame, always desiring to unify things even when that is not possible or illogical.

The universe is not a unit, so there is no expanding of something that is not a unit. Space is infinite, and space is a phenomenon (real, but no attributes of its own).

It is the model, Ethan. It tells us weird things because the model is incorrect.

If you want a workout for the brain? There are two closed systems.

https://fred-rick.medium.com/two-closed-systems-not-one-3d66da5b8dff