The bank should not concern about where the funds are coming from and their's is to serve the clients or the customers of the bank and not to investigate the client private transaction. And letting the bank to know that you holding bitcoin or cryptocurrency is not a bad thing and all depends on the country. If you are in a country that loves cryptocurrency then you are free to tell the bank that you are a cryptocurrency investor. But whereby the country you living in does not accept bitcoin or ban bitcoin then you don't have to expose yourself to anyone to avoid unnecessary embarrassment or harassment.
Stay clear and safe avoid those those who hate bitcoin.
At some point in Nigeria, they were having issues with those who invested in Bitcoin and even blocked their accounts, and I don't even see the reason why the bank should be blocking people's accounts, maybe due to the ill-will of the government. but now that it is becoming legal, the bank will not accept it, and I know some bankers will even have an interest in Bitcoin. The bank sees Bitcoin as a competition, which is why they are trying to get rid of it at all costs. The biggest problem is that you run Bitcoin involving the bank for countries that have accepted it as a legal tender. If in any country Bitcoin is banned, then you will have a big problem with its usage, but if it is not banned, then it makes using it much easier. and you will be free from all kinds of challenges.