You need to add the fields from the AGOL Content page, not via S123.
![jcarlson_0-1629919014197.png jcarlson_0-1629919014197.png](https://community.esri.com/t5/image/serverpage/image-id/21717iF4F91F26A7EB7F28/image-size/medium?v=v2&px=400)
I don't know if that message and overwrite option is a new addition, but I have only seen it when adding fields to the original form in Survey123 Connect.
When adding new fields to additional forms that were created using the "from existing feature service" option, I get a different error that my form cannot be published due to fields not being in the feature service.
- Josh Carlson
Kendall County GIS