Sorry I can’t help you I have the same problem after the update. I also tried to remove the integration and do the setup manually under Configuration -> Integrations to make sure that version 2.3 is set but the problem is still there.
As far as I understand the breaking changes is related configuration via UI for MySensors. I have moved all configuration to frontend and removed it from the YAML configuration (also restarted) and it is still unable to find service notify.mysensors