This is news to me.
https://www.inverse.com/article/25213-darth-vader-bodies-actors
I guess with all the hype over Hayden donning the Vader suit, they didn’t want to publicize this at the time.
They missed out Daniel Naprous who was the actual Vader in Rogue One. Spencers Vader scenes were all reshot ( the inner cape was underneath the chest plate incorrectly during Spencers shoot) so , when doing the reshoots, they got Daniel Naprous to play Vader. Only one shot of Spencer remains in the movie