D.Va's Defense Matrix might be too strong and is undergoing some internal testing. This is according to Overwatch principal designer Geoff Goodman. In a forum post, he wrote about some changes currently being tested for D.Va, including a new attack and weakened shield.
Here is a brief overview of those changes according to Goodman:
Defense Matrix: Energy drain increased by 2x. This means her effective uptime for this ability has been reduced by 50%.
Boosters: D.Va can now use her Fusion Cannons while flying.
New ability - Micro Missiles: D.Va launches a long salvo of small missiles that explode on impact, dealing damage in a small radius around them. This ability can be used while using her other abilities or firing her Fusion Cannons.
Goodman hopes that these changes will allow for a more offensive style of play with hopes that the combination of her abilities will let D.Va deal more damage and put her on better footing against other offensive heroes like Pharah.
"Defense Matrix still remains an extremely powerful tool when timed correctly," writes Goodman, "but the reduced uptime means D.Va won't be able to use it nearly as often overall." Goodman adds that "the goal here is to reduce her reliance on Defense Matrix and maker her more fun to play. As far as balancing goes, we want to nerf Defense Matrix as an ability, not D.Va as a hero."
From the initial testing that Goodman mentions in his post, it sounds as though D.Va will be a little more offense based, which depending on how you play D.Va might be good or bad. Either way, you'll be able to check out these changes in the next Overwatch PTR.