Have the rules around a bye changed?
I agree. However, looking at the results for your tourney, you were not given a bye. You can see that a one point bye was given in the 4th round to the player who finished 7th.

I don't play tournaments often but it seems like a programming mistake to me. You entered the last round tied for first but had no chance to win. There were only 5 out of 25 players available to start the last round so somebody had to get a bye. You should have received a one point bye and finished with 4 points.
I would send a bug report to support@chess.com.