Free Ways to Improve that don’t involve puzzles, game analysis, practice with the computer?

Title says it all. I’ve been playing for over 17 years and want to improve. If there are any free chess books or coaches that are available, let me know. I make about $10k a year so I really don’t consider paying for a subscription or teacher as an option.

I practice with multiple puzzles each day, the computer at the 1200 level, analyze my games, and watch YouTubers. I also do a weekly lesson provided by Chess.com. Earlier this year, I was consistently above 1000 almost 1100 at times in rapid. Now I’m just over 900 and I keep making stupid mistakes like blundering a queen. It’s depressing. They say practice makes perfect but the more I practice, I get more confident. That only gets destroyed as soon as I go on a losing streak to low 900s when I know I’m better than this.

I don’t consider myself a beginner. I did chess club in grade school; taught younger kids how to play; I know the terminology like pins, forks, discovered attacks, hanging pawns, etc. Theoretically, I should be at least 1200 by the end of the year if you were to go by my games I played months ago. Instead, I just do worse. It’s like I’m suffering from a brain tumor where the more I do to improve, the more I suffer.