When adding a new field to ArcGIS Field Map forms with an Arabic field name and after editing the properties of the field, the edits are not saved, and the generic error "Unable to save your form changes
Check the layer settings and confirm that you have the privileges required to make changes" is returned. Additionally, the error message "Must begin with a letter and can only contains letters ,numbers and "_" " is returned under the field name tab when it is in Arabic.
This issue is not reproducible in ArcGIS Field Maps. If the issue occurs, please contact Esri Support Services, as additional information is required for further investigation.