I noticed on some new homes that have prefinished engineered installed that the ends were just slightly raised. It only shows when light hits it a certain way and looks awful. Why does it do this?

That is probably overwood that you are describing. It does look quite bad and that is mostly because of either a cheap builder grade product was used or the installer did not perform the required prep work on the subfloor, or both. It is hard to get a prefinished hardwood floor down without overwood and takes more patience and diligence from the person installing it. New construction is the worst I see because of what I just said

Sounds like an engineered wood, laid over a wet substrate like concrete that has too much moisture vapor emissions.

End peaking is a cupped engineered wood.