When loading a survey on the latest version of the ArcGIS Survey123 field app on IOS 15.3.1 (iPad), the selection for the 'left guardrail' type under the Guardrail field automatically changes itself when a new entry and selection is done within the Guardrail field.
This issue is not reproducible in ArcGIS Survey123 with the provided information. If the issue persists, contact Esri Support Services as additional information is required for further investigation.