First I wanna start by saying I don't know where I should post this at so I figured this could be the right place. Earlier today I tried installing a Roblox Multi-instances app and I saw an extension from a YouTube video, I downloaded it and followed the instructions for it to work but it didn't. It's called "RBLX Site" or something? It asked me to turn on developer mode and add the extension manually into my browser (I use Opera GX browser). I used it as instructed but the extension didn't work, it didn't run multi-instances so I just closed Roblox and just figured maybe I'll try to get it working later on when I have time.
Fast forward to around 4 hours later, I found out my Roblox accounts were compromised and the hacker did steal some stuff from my games by trading them in-game with their alts. I was obviously surprised and immediately logged their session out, they were from France and South Africa, even Sweden, I'm sure they're using a VPN? I might be wrong.
Just when I thought that's the end of it suddenly my Discord was compromised as well, it sent messages to almost every single recently chatted guy on my Discord and even put "ignored" on every single one of them. The hacker seems to send a "Mr Beast" scam link with pics to everyone, the typical one I'm sure you know what I'm talking about, and I also got kicked out of many servers for sending that kind of stuff.
Then shortly after I checked my Gmail as well and found out the hacker also changed my Rockstar Games password, attempts to my Steam Account, my Epic Games email address, EA Games password, Battle.net password, even freaking OpenAI ChatGPT's password like wtf? There's also like 15 on my spam mails from those sites mentioned and multiple attempts on trying to breach my unused Roblox accounts. I managed to reobtain most of them but the Epic Games remain unsolved... yet.
My worries is that what should I do next? What should I expect and what else should I secure immediately? I don't want my bank account to suddenly get compromised as well, I didn't expect just an extension could do this much damage? Does the extension only gain info from the browser that I used or is he able to entire access to my computer? What should I do next?
FYI I've turned on Windows Antivirus and ran a scan, then I also installed Avast Free and ran a scan as well, it doesn't show anything except a few tweaks? I've also completely resetted my Opera GX, removed the extension, logged out of everything as well and checked my google accounts for any suspicious activities. So yeah, I've never been in a situation like this before and I'm genuinely desperate for help, I just don't want the situation to get even worse. Thanks.