You have defined a Job Application field as required="false", but it is still mandatory on the application page.
SAP SuccessFactors Recruiting Management
The application field is defined as required="true" in certain applicant statuses on Job Requisition template.
When multi-status application is enabled, the required attribute can be added to the field application-field-id element to specify that the ordinarily non-required field should be required in that status.
[EXAMPLE] fieldX is mandatory for Recruiter in 'Default' status
<field application-field-id="fieldX" required="true" />
Please review the field permission on Job Requisition template and remove the required="true" attribute from the field application-field-id element.
Job Application, multi-state application , KBA , LOD-SF-RCM-APP , Applicants and Job Applications , Problem