Conflict:
Banks are concerned that crypto could reduce the use of fiat currency and reduce their revenue from services such as credit cards and loans.
Banks are concerned that crypto could be used for illegal activities such as money laundering and terrorist financing.
I assume that you are referring to the Central Bank because commercial banks will always abide by the regulations of the former. Central Banks will always stand against cryptocurrencies because it is decentralized. They are scared that they will lose control of the nation's financial sector. The central banks use monetary policy to control inflation, hence they assume that allowing cryptos is like transferring monetary control to actors in the cryptosystem.
Crypto is the most inappropriate currency to use for financing criminal activities. We shouldn't forget that crypto transactions is recorded on the blockchain and can be accessed by everyone. So transactions can be traced especially if the actors use a centralized platform. But cash fiat cannot be traced which is why it is best to finance criminal activities.
Collaboration:
Banks can use crypto to improve efficiency and reduce costs.
Banks can use crypto to provide new services to customers, such as loans based on crypto assets.
Ultimately, the future of the relationship between banks and crypto is uncertain. However, it is clear that both will continue to evolve and influence each other.
Commercial banks are not against cryptocurrencies because they can always offer profitable services in the sector. Banks can offer exchange services and give cryptos loans and credit facilities. It is the central bank that is against cryptos because commercial banks have more to gain than lose if they integrate crypto services with fiat operations.