If you are a new player or not played for a long time, you'll get a lot of points for winning.
Rating Jumps?

If you are a new player or not played for a long time, you'll get a lot of points for winning.
To add some additional information, players like that will see larger rating changes after games, up and down, until they have more games played in the pool. As more games are played the magnitude of rating changes decreases.
https://support.chess.com/en/articles/8566476-how-do-ratings-work-on-chess-com
A player lost 115 pts when I beat him?
I checked his profile and saw he had earned 205 rating points with his previous win.
How does this work?
Its usuallly like 8 pts when I play someone in my rating range?