Warning! SPOILERS ahead for The Walking Dead: World Beyond season 2 episode 3.
The Civic Republic is a mysterious community that has been slowly teased across each of the airing Walking Dead shows. While it's clearly well-supplied and sizable, its exact location remains unknown. Thanks to a fleet of helicopters, though, the Civic Republic Military can reach almost anywhere, giving the community a lot of influence over the post-apocalyptic, former United States.
Though the CRM has appeared in each of the current Walking Dead shows, it's been World Beyond that has most heavily featured the military group. It's on this show that the Alliance of Three was also first introduced, which is an alliance between the Civic Republic, Portland, and Omaha plus Campus Colony. And it's on World Beyond that the CRM is seen destroying that alliance, first by wiping out Omaha and then Campus Colony with a column of zombies. Now, there are hints the same has also happened to Portland.
In The Walking Dead: World Beyond season 2, episode 3 "Exit Wounds", Hope is beginning to settle in at the Civic Republic's research facility. She s other teens for a party, and through her conversations with Mason, she learns a bit more about life there. Specifically, she learns from Mason that he and other Civic Republic residents are given two weeks each year to go back home. Hope obviously won't have such an opportunity since her home is gone, but she also learns that those who've arrived from Portland don't know when they'll be given a chance to return home, either. It's an odd setup that clearly favors people from the Civic Republic over everyone else, but it's also another hint that like Omaha and Campus Colony, the CRM may have mercilessly and brutally destroyed Portland as well.
Unlike Omaha and Campus Colony, Portland has yet to appear in any of The Walking Dead shows, but World Beyond has referenced it throughout various scenes and character interactions. For example, Dr. Samuel Abbott, the scientist who was originally working alongside Dr. Leo Bennett and Dr. Lyla Belshaw and is now Lyla's test subject, came from Portland. In World Beyond season 2's premiere, during the flashback scene to Omaha's destruction, General Kublek mentions the fact that Portland was becoming increasingly concerned about the breakdown in communication with the other settlements in the Alliance of Three. Portland was likely becoming suspicious of the CRM even before Hope left Campus Colony, and no longer hearing from Dr. Abbott surely raised their suspicions even more.
This latest development of Portland residents currently stationed at the research facility not being offered a chance to go home like their counterparts from the Civic Republic hints that the CRM has now dealt with Portland just as they did Omaha and Campus Colony. They've already collected the best and brightest, so the CRM likely directed a column to destroy the city and kill all those who remained. Mason also mentions to Hope that some of their equipment has come from Portland, which is exactly what happened following Campus Colony's destruction.
While the Portland residents not being granted leave isn't a confirmation that their settlement has also been destroyed, it certainly would match up with the CRM's actions thus far. Clearly, the Civic Republic is looking to consolidate power and resources, and the easiest way to do that is by eliminating their competitors. The CRM upheld the Alliance of Three while it was beneficial, but once it wasn't, they quickly turned on their allies. Since it's known the CRM has already wiped out one of the three, it's not hard to believe they've done the same to Portland in the world of The Walking Dead: World Beyond.