So, a lot of people, including me, have problems with the Targon lore in general. That more spills over to Diana rather than having a problem with Diana specfically.
The Aspects are just horrible, selfish, and idiotic in the way they handle things. The power levels that the story deals with makes every other story, except the Void, absolutely pointless in comparison. And the dramatic shift from the original more personal story between Leona and Diana seems worse to a lot of people.
But Diana in specific has not gotten as much of a pushback as Panth and Leona. However, there still are some problems people have with it.
The first being, that the story reads as though all of Diana's drive got dramatically toned down. Originally, Diana was the one that was intrigued by the Moon and sought out information on the Moon God and discovered the old village herself. In the new lore she was just a troubled child who stumbled upon the reading as punishment. Which, means the Solari were idiotic to have their explicitly banned material on display and put them in the hands of the troubled child. Again, a point of people being dumb for the story to continue (something that happens repeatedly for the Targon lore). Then she just stumbles on the village. Now, this was supposed to show that the Moon God was guiding her, or something. But, again, that's not as interesting as a character actively seeking out and discovering things for themselves.
Then the BIG MOMENT of her Targon lore happens, where she kills the Solari. In the original lore, that was an active choice made by Diana. It set her tone as a villain, even though she was right. Her counterpoint would then be Leona, who was the hero, even though she was wrong. An interesting dynamic to be explored. But in the new lore, it's implied that the Aspect was the one that killed the Solari Elders, again leaving her as just a vessel for the higher power. Taking her another step away from being the driving force in her own lore.
This is later enforced with the Leona lore. You'd think, if these Champions were to be the focus of their story, then clearly their relationship and differing views would be the focus. Leona saw her teachers murdered before her eyes by Diana. That should be a problem. That should probably be the focus of their stories. Instead, Leona gets possessed too, and then she no longer wants to kill Diana, she just wants to discuss her new found knowledge. Again, it's removing agency from the characters and giving it to the otherworldly powers of the Aspects.
And then this is all turned sour when we get Sol. And we realize these aren't even gods. They're backstabbing imperialistic assholes that just attach to people like leeches, and use them to do their bidding. And now Atreus, Diana, Leona, and Zoe (Taric seems cool, for the most part) are all just stuck doing that. Which, when looking at Zoe's story, makes their bidding seem contradictory and downright insane in how they plan things.
, and leaves it open for new lore.
