What stage of the process is your application in? If you've submitted in Oct 2020, most probably they've assessed your PoF and cleared it. You can verify this via GCMS notes. In this case, you don't need to inform IRCC regarding the change of banks as it is irrelevant to them at this point. The only time when you need to show your PoF is when you actually land in Canada, at your port of entry just as a confirmation check. So as long as you are able to prove that the money is always available at your disposal, you are not required to inform IRCC regarding the change in banks.I have uploaded my document before, I got AOR on OCT 29. I was thinking of changing the money from that bank to another, as the processing isnt getting anywhere, and I'm getting more and more stressed about the current financial instability around the bank that i have shown for my proof of fund
However, make sure you have proof that the money is sent & received from you (Account statements/ Transaction references)