What causes they dug and graded and parked right next to my tree during the build, and now it looks bad?

Four injuries usually happen together: roots severed by trenching or footing excavation; soil compacted under repeated equipment, vehicle, and material-storage loads until roots can no longer take up water or air; grade raised or lowered, either burying roots too deep to breathe or stripping them off; and chemical injury from washed-out concrete, mortar, fuel, or paint dumped in the root zone. Nothing shows immediately because a tree runs on stored energy — the crown is being supplied from reserves for one or more seasons after the roots that would have replenished them are gone.