Do I use my druid’s own proficiency bonus for the attacks of their wildshape?

Let’s consider this example: A lvl 12 Druid has a +4 proficiency bonus. They proceed to wild shape into an ape, whose attacks have a +5 bonus to attack rolls, easily calculated to be +3 from its Strength and a +2 proficiency modifier. Does the wildshaped druid attack at +5, or at +7? I’ve seen the first interpretation to be more common but I’d like to know the reasoning for such.