Can a bank feed be undone if there were rules which posted transactions? Can QBO be reversed to a state before the bank feed was done!?

Welcome to QuickBooks Community, sovereignmtd2019.

There's a way if you need to undo the transactions added from the banking. Simply go to the Banking/Transactions tab and select the blue tile of the affected account. From the Categorized section, find the transactions and click Undo.

Once done, these transactions will be posted back to the For review section. You can recategorise them if needed.

Here are some of the articles for more details on how to handle bank transactions:

• Categorise and match online bank transactions in QuickBooks Online
• Reconcile an account in QuickBooks Online

I'll be here if you need anything else. Wishing you all the best!