Ratings can change rapidly when you are a new player or have been inactive for a long time.
Part of the ratings change calculation looks at how active a player has been and makes more rapid changes in those cases so that the ratings can actually get into the right place.
Ratings don't look at your moves or how you played. They just look at whether you won, lost or drew.
I WA BLACK AND A RANDOM IRAQI DUDE IGNORED A SCHOLARS MATE LIKE THING IT IS SUPER OBVIOUS INFACT HE DID THE ENGLISH THEN H4, HE HAD EXACTLY 300 ELO AND I HAD 47 AND HE LOST 200 HE IS NOW 100 ELO NO WAYYY