Hi there. I know the importance of having the same view as our clients' end when accessing their business inside QuickBooks Online. Let me give you insights about this matter.
Once the bank is connected, it will display as connected for everyone's view in accessing the same company file in QBO. In this case, you can verify if the bank is connected at your client's end without any occurring issues, and ensure that you are accessing the exact company file your client is using.
On the other hand, scan this article as a guide when reviewing your downloaded bank transactions in QBO: Categorise and match bank transactions in QuickBooks Online.
Let me know if you have additional queries with bank accounts in QBO. I'm more than happy to assist. Keep safe.