It's a well-known fact that half the reason D.Va's Defense Matrix ability is so powerful is because it can swallow whole ultimates in the game, in many cases making that ult a complete waste.
There's an awkward silence after an ult callout where everyone wonders where it went. Graviton Surge isn't so scary when D.Va eats it on its way out of Zarya's Particle Cannon.
It seems Blizzard decided to make that awkward silence even more cringe-inducing by adding new voice lines to D.Va, which cause her to remark whenever the enemy is unfortunate enough to have their ultimate wasted on her Defense Matrix.
This change is currently live on the Public Test Region; while it's certainly getting a lot less press than Doomfist, it's always good to see a little more sass added to the game.
Some lines are even unique to the ultimate being countered. Soldier: 76's Tactical Visor? "No hacks for you!" My personal favorite is voiced when McCree wastes his High Noon: "I think your clock's off!"
in the ptr dva has a new line, if she eats a pharahs ult with dm she'll say 'im glad i brought an umbrella'— maxington • 14 (@icewalled) July 6, 2017
Though not depicted in the video, she responds to eating Roadhog's Whole Hog with, "I think this pig is a little under-cooked."
Half of the reason D.Va is currently so prevalent in the competitive meta is because of her ability to counter so many ultimate abilities. Sure, Genji can theoretically deflect all the same ones, but it's actually difficult, unlike with D.Va where it can be done often and easily.
It's a common source of frustration for the Overwatch player base because in all other aspects, D.Va is just another tank – not particularly great, nor especially awful. It's this one ability that often makes her a must-pick for a serious team.
There have been petitions to remove D.Va's ability to counter ultimates, and the addition of these voice lines seems to be Blizzard's response.