The information comes from Rod Fergusson , who is the Game Director of Diablo 4. Fergusson shared this information via the Official Xbox Podcast. This of course also means that he hasn’t been able to give confirmations for other versions, even if we expect PS5 not to deviate particularly from the promised performance for Xbox Series X.
On the other hand, there are more doubts about the older generation version, i.e. the Xbox One and PS4 / PS4 Pro family of consoles. We will probably have to wait to confirm the performance of the final version of the game close to its release, i.e. June 6, 2023.
The 60 FPS on Xbox Series is a good confirmation, perhaps taken for granted by many players, but still positive. After all, we’ve recently discovered that Redfall will be capped at 30 FPS at launch (but that’s not the only issue according to some) , pending a patch that introduces a performance mode for 60 FPS. If Diablo 4 had also done the same, there probably would have been even more noise given how much the game is anticipated.