Blockchain.com is known for common bugs but if there's a hack that happened, there's no report or news about it. Those people probably have experienced the bug.
But if it's not the bug, they probably were a victim of phishing for blockchain.com. It's very common that wallet is always the subject by those phishing website makers.
I have not experienced that issues in my blockchain.com account, but blockchain.com is a very popular target of phishing emails I have seen a lot of it coming to my email, but one thing that's interesting to take note is there is an email verification before you can log in to your account and it's an email to approve one's IP, I have to agree with the majority here it's always best to store your coin on a wallet that you own a coin or better a desktop wallet.