Quantum computing can't hold the states for very long and going after BTC seems like a waste of resources, you could go after shitcoins, they're far less resource-intensive to break or legacy finance.
In addition, bitcoin has different address formats, so like Satoshis addresses are legacy and not bech 32 so you'd need to customise it for that too
Finally, if you're going to do a quantum attack you;ll go for the highest value which is satoshis wallet, if those coins ever moved we'd know immediately the chain is not safe and nodes would run updates to protect against it
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