Nothing with ratings has changed like that, but of course lots of things have changed which improves the site since then. One of the largest changes is the old "live chess" interface has been replaced with "Play." It is the same thing as you can play live chess like normal, but aesthetically it looks slightly different, but it also has a lot of newer features like animated emojis or animations on squares if you put them in.
As for rating though, nothing like what you describe has changed. Seems like you just got better 
Maybe your experience carried over and the break helped you refresh yourself mentally so now you play at a slightly higher level! Congrats on your increase 
I first got into chess during early 2021, playing less than a month back then. I remember being stuck on 350-400 elo, then started playing 15|10 (Used to lose a lot of games on time) and managed to get 450 elo before I stopping for more than an year.
One thing that I found odd, however, upon coming back to the game last month was how fast I started gaining elo: I first went back to 400, but then got 300 points in a month, to my current 700 rating. The thing is, I don't exactly remember doing anything different from what I did back then, the only thing I can recall is that now I sometimes watch GothamChess videos (Mainly the "How to Lose at Chess" and "Guess the Elo" series).
Is this all because I don't lose on time anymore, or was there some change in the website?