Zarya is one of my favorite heroes to play, but I would not be mad at tweaking her decay rate (remembering that it was slowed at a time when she was struggling to get value).
I also like playing D.Va, and would love to see her restored as a flexible and decent pick (and it seems like she’s on her way there, which I am happy about).
But I for sure remember long stretches of time—most recently double shield—where Zarya saw relatively little play, and/or was mainly considered Rein’s sidekick. She has no real synergy with Orisa or D.Va, and not much with Ball. She’s decent with Winston, but the last time Winston was meta, D.Va was a markedly stronger off-tank pick for him.
I think the reason she recently saw play with OP!Hog is that Hog’s most natural partner, Orisa, was in the toilet, and shields melted to Hog’s gun. Zarya’s bubble at least gets some benefit if Hog breaks it, and is arguably the best ability to save your teammates from the enemy Hog. Where barriers were not in the game at all, and D.Va was still considered garbage, and Hog (the must pick) has basically no synergy with the hamster, Zarya was the least goofy option as a second tank to him. Zarya and Hog can clearly get work done together, but they don’t do much to actively help or strengthen each other.
I’m not fully convinced that Zarya doesn’t need to be tuned, but it seems to me that she has not been the foundation of metas, but rather a synergistic accessory to them. And the recent balance changes, along with the sledgehammering of the tanks she doesn’t synergize with, has put her in play a lot.
This mirrors what happened to D.Va, I think—she wasn’t monstrously OP, she just played well with the other tanks, and was therefore in play a lot. I’m not wild about how that resulted in D.Va getting nerfed, and I’d be bummed to see that all over again with Zarya.