Got attacked by an infostealer

A few days ago I downloaded a pirated FL studio plugin from a suspicious russian site (yes very smart i know). Having no experience with pirating, I installed it and tried using it. The day after I installed it, my instagram, discord, google and other accounts were compromised. I woke up to my friends asking me why I uploaded crypto reels and scam stories to my instagram, and sending the classic mrbeast scam to everyone on discord.
I reset all passwords and enabled 2fa on mobile, but the hacker was still trying to get into the accounts I didnt think of changing my password on.
I swapped my infected ssd with my old one, but a few days later, as I was playing a game on steam, I got a steam chat saying “pls accept bank” from an account that I did NOT friend but was friended. Then I got a notification from the bank requesting 50€ from the card I use for steam. I immediately froze it and reset my steam password from my phone.
How could the malware have traveled through SSDs? Maybe I didn’t remember to change my steam password? (Not likely)
The pc is currently disconnected from ethernet and is rotting at my desk. I’m thinking of formatting since it’s an old SSD and 15 year old me may have downloaded malware on that too, but I don’t know if that will completely wipe the whole pc since its not connected to the internet and it’s gonna use a local reinstall.
What should I do?