However, from your explanation, there is one thing I want to ask, does that mean we are still safe from quantum computing attacks by using a new wallet or generating a new address on the same seed phrase ?
Anytime you make transaction, your address public key is known already. If quantum computers is able to be used to access bitcoin private key, it will not be through bitcoin address but through the public key. If you used a bitcoin address to receiver bitcoin but you did not send the coin to another address or anyone, the public key can not be known and can not be attacked in the future with the use of the quantum computer.
So what d5000 (OP) is saying is that you should move your bitcoin to the address that you have not used to make transaction before so that your public key is not known to anyone but only you. Fees are low now which is a perfect time to transfer the coin to a new address.
Okay, I understand that it is recommended to use a new address and has never made a transaction. So does that mean we can use a new wallet (or generate a new address) that comes from the same seedphrase? or is it better to create a wallet from a different seedphrase? I didn't get an answer to my question, or maybe I don't understand your explanation. I hope OP or those of you who understand can also answer this, because I have little knowledge about it and really care about this security thing.