https://www.gamespot.com/articles/destiny-2-cayde-6-actor-replaced-for-next-expansio/1100-6460484/

One of the funniest, most lighthearted characters in the Destiny universe, Cayde-6, has been up until this point voiced by veteran TV and video game actor Nathan Fillion. But he isn't coming back to voice Cayde-6 in Destiny 2: Forsaken, which could be the character's final appearance in the Destiny series.

Fillion told Kotaku (via IGN) that he was not available to voice Cayde-6 in Destiny 2: Forsaken, presumably due to scheduling conflicts (he is a busy person). He also confirmed that he did not voice Cayde-6 in Forsaken's E3 trailer.