Version = "0.19.0"
IN rpc/core/routes.go line 37
// abci API
"abci_query": rpc.NewRPCFunc(ABCIQuery, "path,data,height,prove"),

IN rpc/core/abci.go line 50
func ABCIQuery(path string, data cmn.HexBytes, height int64, trusted bool) (*ctypes.ResultABCIQuery, error)

the route defined that the ABCIQuery needs four params: "path,data,height,prove".
In other side the ABCIQuery func defined four params: "path,data,height,trusted", in which trusted is not required and default value is false.

Problem:
When ABCIQuery call proxyApp the 'trusted' translated into ‘Prove' by operation !trusted.
So the abci app always gets the 'Prove' with true value.

Fix: change the routes definition to:
// abci API
"abci_query": rpc.NewRPCFunc(ABCIQuery, "path,data,height,trusted"),