Why is my rating dropping so fast? I can't seem to improve. Any tips?

Play longer time controls, and analyze your games afterwards.
Not with the engine for 45 seconds, but played out on a physical board, taking notes of what you did wrong.
This will make what you learned in that game stick, unlike seeing the engine say that you made a blunder on move 25.
Also, pick one of the main areas of chess to study, and do so.
Decide between positional play, tactics, openings, and endgames.
Whichever you are weakest at, start there.
I recommend getting a book or online course to study.
Although I’m sure there is enough content on the internet for free, although not as convenient or in one place like a specific course or book is.
Additionally, play through master games swiftly, spending no more than 10 minutes per game.
Choose master games which feature your openings, so you can over time build a proper idea of how these positions should be handled.
If you do that for a half an hour a day, you can easily complete 100 such games a month.
Keep doing tactics, and, be sure to retry your failed puzzles.
This is needed because tactical strength is essentially just familiarizing yourself with new patterns, until they become intuitive.
By redoing these failed puzzles, you are building recognition for a pattern that you are inexperienced with, changing “unfamiliar tactical themes” into familiar ones.
Strong players are familiar with an absurd number of these tactical combinations, so this is essential to becoming a strong player.
Good luck and hopefully you make 1500 some day! :)