I’m glad you went to the vet 2 weeks ago, but did the vet examine her? Usually when a bunny sits still without any exercise like that daily, there’s something wrong. If her teeth are not grinding, then she’s not in pain. I would check her eating and pooping next. Are they normal? Is she binkying ever? Running? Walking with any difficulty? It’s possible that it is not related to the other bunnies at all, so I would rule out illness first.
If her health checks out, and it is behavior, it sounds like the changes don’t agree with her. Try to set up her habitat as much like it was in the former place. Check the rooms for smells you may not have noticed that is putting her off. Let her out into a different room that she can explore. See if she has lost interest in treats. Depression happens when a bonded pair is split up, usually when one dies, but is not the first thing to look for when a bunny is not behaving normally. I would get her a check up next.