Willow quantum chip demonstrates verifiable quantum advantage on hardware

The rule of thumb is that a working quantum computer that can run Grover's algorithm reduces the security of a symmetric cipher to half of its key size. That is, AES-128 should be considered to have a 64 bit key size, which is why it's not considered "quantum-safe."

Edit: An effective key space of 2^64 is not secure according to modern-day standards. It was secure at the times of DES.

AES-128 is quantum safe (more or less). 64 bit security in the classical domain isn't safe because you can parallelize across 2^20 computers trivially. Grover gives you 2^64 AES operations on a quantum coputer (probably ~2^70 gates or so before error correction or ~2^90 after error correction) that can't be parallelized efficiently. AES-128 is secure for the next century (but you might as well switch to aes-256 because why not)

Is AES-256 more quantum resistant? It still has 16byte block size, so intuitively it should be equally vulnerable to Grover.

Grover's algorithm is sqrt(N) wrt domain size and the key is part of the domain of the function.