When an ArcGIS Online organization has multifactor authentication enabled and enforced, SAML accounts exempted from the multifactor authentication enforcement returns the "Your organization requires Multifactor Authentication (MFA)" prompt after opening ArcGIS Survey123 from the app launcher.
Sign in to ArcGIS Survey123 directly from https://survey123.arcgis.com/. Depending on the identity provider (IDP), doing this in a new browser session may be required.
In the prompt, click Cancel > Leave.
Sign in to ArcGIS Survey123 again using the URL of the organization.