Hi there, Victoria. When your transactions stop syncing to your QuickBooks account, it's possible that your bank updated its security or is having maintenance protocols that can pause the sync with QuickBooks.
I recommend logging in to your bank's website and checking for any alerts regarding updated Two-Factor Authentication or any ongoing maintenance.
If everything looks fine on the bank's website, you can manually upload those transactions into your QuickBooks bank feed by logging in through a web browser. Download your transaction history starting from January and click the Upload bank statement button.

Don't hesitate to reply here in this thread if you have more concerns related to QuickBooks. We're here to help.