you realise that if your rapid is higher rated than your blitz and bullet (in your case 400 point which is a massive difference) your rapid games would be harder to play than your blitz and bullet games so it is easier to lose points. Also thats more of a 'you' thing different people get better and play better in different ways. Also the blitz pool are that strongest if you are playing a tc such as 5 min, 5|5 or even 3|2 since most of the poeple playing those modes have extremely high rapid ratings. Similarly with 2|1, 2 min or 1|1 bullet since most people who play those have extremely high blitz ratings
Bullet and Blitz bad for your chess.

Yah, but in my case, playing blitz and bullet is harder than rapid, and I dunno why. I suggested two theories I have in my op
I have a better suggestion your calculation skills are good and your board vision and pattern recognition is bad. I'm much higher rated in rapid than blitz or bullet and I know why its because i lose games by blundering pieces in one move not miscalculating. I would guess you are the same and blunder in time control due to poor bored vision and pattern recognition. I would bet playing blitz makes you want to play faster so you get lazy and move too fast then blunder. Also it could be that its not that your playing blitz makes you worse but choosing not to use that same time on rapid makes you worse at rapid again you have over simplified too many things. In my experience rating for rating players know more opening theory at 1200 blitz than 1500 rapid but this kind of makes sense as a blitz player has no time to figure out a move on turn 4 it needs to be memorized. Most the best players play blitz online but each time control is different too like 45/45 players in my anecdotal experience are weaker than 15/10 players even though both are rapid ratings. In either case it sounds like you need to practice the same things i do board vision. I just played a Dailey game where I won a pawn the a piece and dominated him almost the whole game then hung my queen in one move. I moved my queen that turn right next to the enemy queen on a diagonal in my mind it didn't even register my queen was hanging. If this sounds like you that is why some people are better at calculation I have spent 5-10 minutes calculating lines with explorer in daily that start with full pieces blunders only to realize after i go all the way back to check another line that y first move hung a rook. Blitz and slower time controls do not feel the same at all the strategies are different when i first started playing bullet i got a higher rating going for flags not even trying to win games. I would say playing some of all the time controls is good for you as a player and that playing blitz does not make you worse at rapid that's a bad assessment.

I have had instances where I start a calculation and then I realize midway through “oh wait my pawn is hanging”

Blitz and Bullet are good for testing out lines of opening play in a rapid fashion (no pun intended!). They're also good for some quick games when one may not have time for a Rapid-level game.

Play Longer Time Controls...
For many at the beginner-novice level, speed chess tends to be primarily an exercise in moving pieces around faster than your opponent while avoiding checkmate, in hopes that his/her clock runs out sooner than yours. And/or hoping to notice and exploit your opponent’s blunders while hoping they don't notice yours. The reason for this is that there is little time to think about what you should be doing.
It makes sense that taking more time to think about what you should be doing would promote improvement in your chess skills and results.
An effective way to improve your chess is therefore to play mostly longer time controls, including "daily" chess, so you have time to think about what you should be doing.
This is not to suggest that you should necessarily play exclusively slow or daily time controls, but they should be a significant percentage of your games, at least as much, if not more so than speed games which, while they may be fun, do almost nothing to promote an understanding of how to play the game well.
Here's what IM Jeremy Silman, well-known chess book author, has to say on the topic...
https://www.chess.com/article/view/longer-time-controls-are-more-instructive
And Dan Heisman, well-known chess teacher and chess book author…
https://web.archive.org/web/20140627052239/http:/www.chesscafe.com/text/heisman16.pdf
https://www.chess.com/blog/RussBell/dan-heisman-resources
and the experience of a FIDE Master...
https://www.chess.com/forum/view/general/how-blitz-and-bullet-rotted-my-brain-don-t-let-it-rot-yours

Play Longer Time Controls...
For many at the beginner-novice level, speed chess tends to be primarily an exercise in moving pieces around faster than your opponent while avoiding checkmate, in hopes that his/her clock runs out sooner than yours. And/or hoping to notice and exploit your opponent’s blunders while hoping they don't notice yours. The reason for this is that there is little time to think about what you should be doing.
It makes sense that taking more time to think about what you should be doing would promote improvement in your chess skills and results.
An effective way to improve your chess is therefore to play mostly longer time controls, including "daily" chess, so you have time to think about what you should be doing.
This is not to suggest that you should necessarily play exclusively slow or daily time controls, but they should be a significant percentage of your games, at least as much, if not more so than speed games which, while they may be fun, do almost nothing to promote an understanding of how to play the game well.
Here's what IM Jeremy Silman, well-known chess book author, has to say on the topic...
https://www.chess.com/article/view/longer-time-controls-are-more-instructive
And Dan Heisman, well-known chess teacher and chess book author…
https://web.archive.org/web/20140627052239/http:/www.chesscafe.com/text/heisman16.pdf
https://www.chess.com/blog/RussBell/dan-heisman-resources
and the experience of a FIDE Master...
https://www.chess.com/forum/view/general/how-blitz-and-bullet-rotted-my-brain-don-t-let-it-rot-yours
please help I am 2200 and me and my opponents are doing the same things you are saying in blitz, please assist us with your wise knowledge.

Play Longer Time Controls...
For many at the beginner-novice level, speed chess tends to be primarily an exercise in moving pieces around faster than your opponent while avoiding checkmate, in hopes that his/her clock runs out sooner than yours. And/or hoping to notice and exploit your opponent’s blunders while hoping they don't notice yours. The reason for this is that there is little time to think about what you should be doing.
It makes sense that taking more time to think about what you should be doing would promote improvement in your chess skills and results.
An effective way to improve your chess is therefore to play mostly longer time controls, including "daily" chess, so you have time to think about what you should be doing.
This is not to suggest that you should necessarily play exclusively slow or daily time controls, but they should be a significant percentage of your games, at least as much, if not more so than speed games which, while they may be fun, do almost nothing to promote an understanding of how to play the game well.
Here's what IM Jeremy Silman, well-known chess book author, has to say on the topic...
https://www.chess.com/article/view/longer-time-controls-are-more-instructive
And Dan Heisman, well-known chess teacher and chess book author…
https://web.archive.org/web/20140627052239/http:/www.chesscafe.com/text/heisman16.pdf
https://www.chess.com/blog/RussBell/dan-heisman-resources
and the experience of a FIDE Master...
https://www.chess.com/forum/view/general/how-blitz-and-bullet-rotted-my-brain-don-t-let-it-rot-yours
This doesn’t really answer my question. I’m moreso asking why, whenever I play blitz I
1. Do worse than rapid despite being rated 400 points lower
2. How that translates to me doing WORSE (not even stagnating like that forum you posted, I’m simply playing worse than I usually do)
Bullet may not help you improve, but it is massively more enjoyable. If chess can be enjoyed at all.
So, I’ve noticed a trend. Whenever I play bullet and blitz, I play worse. Then, when I switch to rapid, I keep playing worse and my rating plummets, and when I stop playing them, my win rate skyrockets.
I’ve heard two reasons for this. One, because the rapid pool is worse than the blitz and bullet pools, and a majority of the “good” players play blitz. And also, that you’re just playing faster when you play blitz and bullet and it makes you play worse. Idk. Give me answers.
(that being said, when I decide to play an 8 hour game someday I’ll play at GM level
)