I would say I saw some defensive lobs. A few. Usually to keep her in the point. Nothing strange.
And I saw a lot of deep topspin shots that did bounce high behind the baseline.
O'Brien was playing the same way.
But, I didn't see that Montreal match.
The worst case of moonballing I've ever seen was Pratt, I think it was against Li.
I don't complain about this tactic, both for variety, and if it works.