I'm here to provide some insights about the balance.
Your QuickBooks balance is the total amount of all the transactions added and matched from the Banking page. Make sure to add those pending transactions, so you have an accurate report.
The other possible reasons why the balance is off are the following:
Outstanding transactions.
New transactions for a connected account.
Duplicate transactions.
Edited or deleted transactions.
Card (liability) account.
You can fix the incorrect balance by making sure to review the following: