It's possible that you've added the downloaded transactions instead of matching them to the existing ones. This will result to duplicate transactions and can cause bank discrepancies. We can go back to your banking page so we can review it to make sure that we've matched them.
Let's undo them first:
From Banking, select the Reviewed tab.
Locate the transaction and select Undo under the Action column.
Go back to the For Review tab. Click on the transaction and select Find match.
On the Match transactions window, locate and check the match/similar transaction you created in QuickBooks.