At the moment we are a group of several victims of the company Block chain dot com and we entrusted our funds to Block chain Luxembourg and lost over 400 bitcoins, this amount is worth today about 4.5 million American dollars.
We are sure we didn't do anything what could influence to the security of our wallets which were used at blockchain com (generating paper wallets, storing passphrase, etc). In most cases we were using Apple environment (mainly newest iPhones and official blockchain app).
Unfortunately I must say, welcome to the club of those who lost their coins in similar way. You all have in common that you used iOS and the official blockchain app for the same OS. Given that there are many cases of this kind if you search the internet, I have no doubt that there is some exploit that allows hackers to clear accounts of users.
Another curiosity when it comes to blockchain.com (info) wallet, some users lost coins in a rather bizarre and mysterious way.
Thoughts on this private key stealing mystery