Cavendish Experiment

Gravity Not a Constant
Scientific American explains that, unlike other fundamental forces in physics, gravity cannot be accurately measured.

Puzzling Measurement of "Big G" Gravitational Constant Ignites Debate

Measuring the Very Small
Physicist Jens Gundlach explains that gravity is very hard to measure and would require measuring the force equivalent of the weight of a few human cells on two one-kilogram masses that are one meter apart:

Gundlach explains that there are many effects that could overwhelm the gravitational effects. Static attraction, among other effects can easily overcome such gravitational attraction.

Wildly Erratic
The article explains that the results are wildly erratic.

The values of these sophisticated laboratory experiments differ from one another by as much as 450 ppm of the constant. The weight of a few cells on the masses of the experiments involved, for context, is significantly smaller than 450 ppm.

While they may be measuring something, such as an unaccounted force, the results are erratic, and are subject to change.

Cannot Be Measured
The end sentence is plain, and tactically admits that they cannot measure gravity.