Should ESRI check and fix this as soon as possible as my users can see others' records by going through survey123.arcgis.com?urlPortal= connect to enterprise portal. The feature service was correctly set up so only submitter can see and edit his own account
Sounds like survey123.arcgis.com?urlPortal=... bypass the control on feature service
Can you check the sharing settings on the feature service and any associated views? If it is public at a feature service level, users will be able to see all features if they access the URL directly.
Survey123 leverages the portal sharing mechanism. It can't override it. You need to have the service shared to allow for editing (form submission). Additional views can be used to share results.