So many good boss fights are missing from that ending. I guess it also isn’t communicated all too well to the average consumer that there are multiple endings to FS games, though. You have a hunch that it’s not the way the game is “supposed” to end, but you don’t know for sure. Chances are you’re somewhat interested in a repeat playthrough if you came that far and beat Isshin, however, so you’ll likely see a different ending then