The article says that this proves that Einstein's equivalence principle (resulting in relativity) holds in this test of a falling quantum particle (where gravity results in a phase shift in the quantum state).

It doesn't show/prove how general relativity and quantum mechanics interact.

NOTE: The Dirac equation and Quantum Electro Dynamics (QED) unify quantum mechanics and special relativity (non-accelerating frames of reference).

So the remaining piece is either to extend QED/QCD to accelerating frames of reference or to quantize general relativity. That would likely predict the phase shift observed in this experiment.

From the article: "The result does not unite quantum mechanics and gravity, nor does it show that gravity itself is quantum".

I must say, it's actually quite refreshing to read an article about a science topic that conveys the caveats and limitations of the study. Far too many of these studies get filtered through the news outlet hype-machine