Its saying my highest rating was 1780, but I clearly see that it was 2k. This is the all time statistics. So I can't say it is for the new year only.
Puzzle Rush Glitch??
go to your main menu ---> press the puzzle rating on your right side of the screen ----> press on the light blue line like in the heading of this forum ---> change the time to 'All time'
That's the Puzzle graph, not Puzzle Rush. The graph still shows data from before the puzzle ratings changed. Before October, those are the old ratings. Stats are only valid for the new rating system.
https://www.chess.com/news/view/announcing-new-puzzles-rating-system
It's not a bug, it was design decision to keep it that way initially. There's work being done to change the graph to reflect the new rating system for your whole puzzle history.