If you run into QuickBooks WebConnector error that the Teapplix application has a revoked certificate, Intuit has posted a fix on their site:
This seems to involve downloading a program file and directly replacing your existing file with the newly downloaded file. They posted version for 2021, 2022 and 2023 version of QuickBooks, we do not know if the 2021 version will work for older version of QuickBooks. It does not hurt to try it and you should contact Intuit support if the version does not work for you.