His whole motive for returning was confusing, especially when it seemed he found happiness with Brienne.
It just didn’t make much sense given how far his redemptive arc had come, and the same can be said for each character in some regard.
There’s plenty of other examples, but another glaring character shift is Jaime Lannister, who decided the people of King’s Landing suddenly didn’t matter despite him explicitly stating in earlier seasons he cared for them so much that he became the Kingslayer.