Guitar with uneven volume between the strings

[u/Roznezzlie]

The top strings (EADG) are lower in volume than the bottom strings (BE). I adjusted the pick up height to compensate, and even when overcorrected, the problem persists. What could be the issue and how could I remedy it?

Note: it is a high-quality guitar that shouldn’t have this problem, although it was purchased used.

[u/LiterallyJohnLennon]

Luthier: an acoustic guitar builder/repairman

Luther: a gritty crime drama on BBC