Covid played a factor in season 3. New Zealand was locked down, and Ebony Vagulans couldn't be there. Thus, the new character of Beth. Ebony was able to eventually get in, but then both the actresses got covid at different times, and lines were switched back and forth. According to the TV Fanatic interview with Lucy Lawless that came out on October 10, 2022.
Lucy Lawless and Tatum Warren-Ngata appeared together in the New Zealand TV movie Toke (2020). Which is how Lucy Lawless came up with the idea to get her to play the part of Beth when Ebony Vagulans wasn't able to be there due to covid.
Tatum Warren-Ngata, who plays new character "Beth" starting with this episode, previously appeared in Episode 5, Season 2 - as the murder victim, "Sam Turei".