Chess struggles

Sounds to me more like a tilt or burnout problem than an objective one with chess.
It sounds like you've been working on chess really hard and perhaps suffering from burnout without knowing it. Usually taking a break from chess for a few days (less than a week) can help you "reset."
The ratings naturally swing up and down a lot though. That is normal and not much can be done about that. The best you can do is minimize them with my Stop-Loss System, or you can learn about tilt and how to prevent that. I also have a video almost on hour long on the 7 types of tilt and how to cure each of those types:
@1
"my main trajectory has been downwards" ++ Analyse your lost games.
"I started watching some chess coach videos on YouTube like ChessCoachAndras" ++ Not useful
"i have tried theoretical openings" ++ Does not matter
"dubious and crazy openings" ++ Does not help
"How do I turn my playing level and skill and results around?" ++ Analyse your lost games.

I've written several posts aimed at helping players like you who might not be able to afford a coach. Here are some links to those posts:
1. How to Improve at Chess: Ultimate Guide
[https://www.chess.com/forum/view/for-beginners/how-to-improve-at-chess-ultimate-guide]
2. Jumpstart Your Chess Journey: Proven Tips for Beginners [https://www.chess.com/forum/view/for-beginners/jumpstart-your-chess-journey-proven-tips-for-beginners]
3. From Good to Great: Mastering Piece Arrangement on the Board [https://www.chess.com/forum/view/chess-lessons/from-good-to-great-mastering-piece-arrangement-on-the-board]
4. Dominating the Board: Mastering Aggressive Moves in Chess
[https://www.chess.com/forum/view/general/dominating-the-board-mastering-aggressive-moves-in-chess]
5. Outsmarting Opponents: Creating and Exploiting Weaknesses
[https://www.chess.com/forum/view/general/outsmarting-opponents-creating-and-exploiting-weaknesses]
6. Piece Domination 101: How to Neutralize Your Opponent's Forces
[https://www.chess.com/forum/view/general/piece-domination-101-how-to-neutralize-your-opponents-forces]
7. Mastering Piece Trades: Transforming the Chess Battlefield [https://www.chess.com/forum/view/general/mastering-piece-trades-transforming-the-chess-battlefield]
8. Practical Endgames Demystified: Techniques for Victory [https://www.chess.com/forum/view/general-chess-discussion/practical-endgames-demystified-techniques-for-victory-95628525]
I hope you find these resources helpful in your chess journey. If you ever feel like you'd benefit from personalized coaching, feel free to reach out to me. Keep up the good work and remember, every game is a learning opportunity!