I did some research about that matter, and found an article that answer it: https://support.chess.com/article/210-how-do-ratings-work-on-chess-com
Basically, this is because Chess.com hasn’t seen any games from you in a while, and there is no way to tell whether you’ve been practicing and getting better other places, or if you haven’t been playing at all. I have seen your rapid games, and I think you were playing in each while a game.
I hope this isn't a terribly stupid question, but I've noticed since my rapid rating passed 1300 or so, suddenly each win/loss resulted in around +/- 15 or 20 rating points, instead of the usual 7-9 points. I've looked at the recent games of my opponents at a similar level, and their games are resulting in rating changes of 7, 8, 9 points. Is there a mathematical or other reason for this?