Have you heard or read recently about about BIP360? It was proposed to solve the issue of bitcoin not to be vulnerable to quantum computers.
People that can be affected to the vulnerability are those that their bitcoin address public key are known to the public. Do you know that when you make bitcoin transaction, the public key of the address used to make the transaction is no more only know to you? It is known onchain.
Roughly 25% of all bitcoin have revealed a public key on-chain; those UTXOs could be stolen with sufficient quantum power.
That is not small at all. Also it is predicted that if someone or some people are able to use quantum computing to know some private keys and the coins stolen, the people may prefer to do it in a way people will not know until it silently got to the point that people will know. But I doubt if such people will leave those Satoshi P2PK transactions holding multi billion dollars of coins today. But in short, it is good if bitcoin is moved away from ECDSA/Schnorr signatures.
ECDSA was used for almost everything about signing before Taproot
Schnorr is used in Taproot.
These are important information:
This proposal follows the implementation of post-quantum (PQ) output type (P2QRH) and introduces a pre-announced sunset of legacy ECDSA/Schnorr signatures. It turns quantum security into a private incentive: fail to upgrade and you will certainly lose access to your funds, creating a certainty where none previously existed.
Phase A: Disallows sending of any funds to quantum-vulnerable addresses, hastening the adoption of P2QRH address types.
Phase B: Renders ECDSA/Schnorr spends invalid, preventing all spending of funds in quantum-vulnerable UTXOs. This is triggered by a well-publicized flag-day roughly five years after activation.
Phase C (optional): Pending further research and demand, a separate BIP proposing a method to allow quantum safe recovery of legacy UTXOs, potentially via ZK proof of possession of a corresponding BIP-39 seed phrase.
I think that quote and image is self-explanatory. You can read about it from here in details:
https://github.com/jlopp/bips/blob/quantum_migration/bip-post-quantum-migration.mediawiki