question.

Here's why:
Rating Deviation (RD):
The Glicko-2 rating system (often used for online chess) includes an RD value that represents the uncertainty of a player's rating.
New Accounts and Few Games:
When a new account is created or a player has played few games, the RD is high, meaning the system isn't very confident in the player's rating. Therefore, rating changes (both gains and losses) will be larger.
Established Ratings:
As a player plays more games and their RD decreases, the rating system becomes more confident in their rating. This results in smaller rating changes, even if they win or lose against players of similar or different ratings.
Playing Higher Rated Players:
Winning against higher-rated players will still result in a larger rating gain than winning against a lower-rated player, but the difference in rating change between a 100-point win and a 10-point win will be smaller as the player's rating stabilizes.