ECDSA/secp256k1 is quantum-resistance as long as it's public key isn't known, which means users should be fine as long as they never re-use their Bitcoin address and Quantum computer isn't fast enough to find out it's private key before the transaction got confirmed/fully propagated to all nodes.

But there are proposal to use cryptographic signature which is quantum resistant, even though AFAIK there's huge trade-off such as far larger signature size and longer verification time.