You'll want to log in to your PayPal account to see if there are announcements about third-party connections. If there's none, please contact the PayPal support team to check if they have updates on your account that affecting the connection with your QuickBooks account.
There's currently an ongoing investigation with the issue you've provided. If you haven't already, I'd suggest contacting our phone support department for help. They can add you to the list of our affected users. This way, you'll receive updates about this investigation via emails.