On a new construction, there is a lot of water standing in the gravel of the rough-in of the shower drain. Is this a concern?
Hard to say. Too many variables. But, typically, not what you would see.
I assume this is a rough-in before basewment slab pour?
Is the ground frozen? Thaw before pour.
High water table? Take drainage precautions.
Excess water run from somewhere else? Dry it out.