There were definitely hints that made it clear if you looked at all of them and thought about it for a bit, but it was hardly an obvious spelled out twist, it did require some degree of piecing the clues together.
On a more general note though this is why twists generally are difficult to pull off in stories with large fanbases like this. Someone is eventually going to stumble upon the correct outcome, and once it gains traction it will just become increasingly obvious once more hints are added.
The important part is whether the twist works in context, and whether it is a twist in-story, which I would say it is. Necrolord players should probably have pieced it together earlier in-story, but given the limitations of 4 distinct stories it works well enough.
- - - Updated - - -
Let us not forget the lesson of GoT season 8. Just because you didn't anticipate it doesn't make it a good twist.
If all you want is shock value then you could have made the Primus Zovaal from the future, or something equally absurd.