There are around 6.8 million BTC deposited in addresses vulnerable to a potential quantum computing attack.
Around 6,786,955 bitcoins (BTC), equivalent to nearly USD 626 billion, are currently in a theoretical vulnerable state against quantum computing attacks, as they are associated with addresses whose public keys have already been exposed on the network.
That amount represents approximately 33% of the total bitcoin supply.
According to the Project Eleven website, 13,778,861 addresses with non-zero balances and revealed public keys were identified, a necessary requirement for an attacker, in a future scenario with sufficiently powerful quantum computers, to attempt to reconstruct private keys.