When Star Trek: Voyager was nearing the end, the producers introduced a romance between Robert Beltran's Chakotay and Jeri Ryan's Seven of Nine. The fans didn't see that one coming as there'd not previously been any type of chemistry between the two characters, and the relationship just didn't make sense. Nevertheless, Voyager ended with the pair still a couple as far as we knew.
Before the beginning of the second season of Star Trek: Picard, Beltran was contacted about a part in the first two episodes of the season, which were "Penance" and "Assmiliation." [Via Slashfilm] In those two episodes, Admiral Picard and his crew are sent to an alternate timeline by Q where Earth is an evil empire ruled over by a fascist dictator and her husband. Ryan's character was the president of this evil Earth, and Beltran was offered the role of her husband, which was played by Jon Jon Briones after Beltran turned it down.
Chakotay would have been the First Magistrate of Earth and have been just as evil as Briones' character, and that didn't appeal to Beltran who acknowledged he'd turned down the role on Twitter/X.
"I was offered an episode (first two, then one) in 'Picard,' but I simply did not like what they had written for Chakotay, so I turned them down. I won't go into detail, but I have no animosity toward the 'Picard' producers at all. 'Star Trek: Prodigy' offers a Chakotay that I AM enthusiastic about.""Robert Beltran
Voyager never visited the Mirror Universe so we never saw the vicious side of Chakotay , and though Robert Beltran has played characters that have less than stellar qualities, perhaps he simply wanted to protect what he'd created with Chakotay. As Captain Janeway's second in command, he was fiercely loyal, dedicated to the crew, and determined to help the Voyager team make it home. That's a legacy to be proud of, and not wanting to tarnish that image is laudable.