What happened?

Back in May, I was a 800-rated player. I took a big 6-month break because I didn’t seem to improve. I was not aware of the word “tilt” at the time. During winter 23-24, my friend completely ran up the rating later (1000-1700). He convinced me to join a local tournament in July. I got excited because I wanted to play in my second-ever big tournament. I absolutely grinded and climbed high, all the way up to 1300. In the tournament (U1100 USCF, I was 600 USCF at the time and got over-confident and played up instead of playing U700), I got 2.5/5. That was a foolish decision. No worries! Anyways, because they were higher-rated than me, I still got rating. I did learn my lesson, I’m not ever going to play up again. Then, I go to my computer, a week later, and drop to 1200 chess.com. Not happy, but it’s tilt and it’s normal. I got it back at the end of August. I keep playing. I keep bouncing up and down with 1300 and 1350. This is still happening right now. I’m not improving, but why did I stop so sudden? Shouldn’t I gradually reach my fluctuation when I peak? I am so confused. My breaking point for being concerned is when my friend, who I could regularly beat, got me in a tournament. What happened? I’m planning to stop studying by myself and going to my local chess club, but why did I stop so abruptly? Am I peaked already?