I need Help!

So i finally made it to platinum and i was really happy because i never in a million years imagine that i could achieve something like that in a fighting game.
I thought that "Wow all my hard work has payed off"
However, my derpy ego would soon be deflated after being matched with players ranging from Platinum to Ultra Diamond.
I came to the realization that, "HOLY COW! I don’t know anything about this game!"
I literally felt like i was on Bronze again. :confused:
And i get, of course those players would be stronger, but whenever i achieved a rank up like gold
I would still lose to super gold players, but the skill gap between both ranks didn’t feel so impossibly huge.

I’m a Karin player & I still struggle with certain match-ups and i lose to some Super & Ultra gold players
What should i be doing?

Should i be focusing on one specific match-up?
Should i take the time to learn how to play with the character i’m having trouble with so i can get a better understanding of the character?
How long should i practice in training mode?

I just want a proper training regime.

Any advice would help me greatly.

Different avenues for different players, and it’s hard to say without analyzing your gameplay.

Do you control your character correctly? Can you dictate the spacing of the screen? How are you punishing? Can you control the air efficiently? Are you confirming cr.mk hits? Can you get maximum damage from your confirms? Do you know how many frames are inbetween each hit of your block strings? Do you know your characters frame data?

Character specific stuff comes after you’ve completely polished up your general strategy.

Well my cfn fighter ID is Momochii if you want to look up some of my matches

And far as my own character goes. I pretty familiar with Karin
Like I know that her “Go-to” spacing is moving in and out of her st.mk to cr.mp range
I’m solid with confirming with cr.mk as well as st.mp
I’m still working on optimizing my damage
And I regularly look up my character’s frame data.

I feel like most of my problems stem from other characters

How many hours do you take learning a specific match-up?