I am currently receiving this message for my "Clear the Air" survey (https://survey123.arcgis.com/surveys/465311af1fb845a8a4b08b843c82e2bb/overview ) when users attempt to access it via the QR code on their smartphones. You can access the survey if you use the link generated on the Collaborate tab on a PC. This was first reported to me at 10:30 today 4/9/2019.
The data is viewable on the Survey123 website. The ArcGIS Online Health Dashboard does not report any type of general outage. The survey was created using Survey123 Connect.
California State University San Marcos