Everything was looking legitimate. This message was looking exactly the same as any other notification on fbc site. Same fonts, same colors, etc.
Now everything works as usual, so I guess I will never know what happened.
It doesn't look legitimate when you see such a message and someone asks you to contact them on their protonmail email. I know that Protonmail is used for privacy purposes but no company should write you or contact you with Proton email because they are LTD, they have responsibilities and they shouldn't be the one protecting their privacy on that level. Company should be public, open and should be using their own email servers instead of Proton.
So, asking for deposit and contacting on telegram or protonmail was already a red flag.
By the way, I don't understand what happened exactly, was that problem on your router? Or were all of your computers infected? Or was it actually the problem from Freebitco's side?
This actions should consider as red flag by people since if they don't have doubts on what they can read on their email then provably they will be compromised by some idiots trying to replicate them. Also if there's important details involve that ask to provide, to download or asked for some amount for certain verification and other more suspicious then people start to doubt and always verify what they receive to the management so that they can get an answer if they legitimately sent that email or not.
Maybe those frauds just find new method on how to contact those people using protected emails that's why they came to the point on why they contact several guys on their target list.