Guest User Security Restrictions
Beginning with the Winter '21 Salesforce release, Guest Users, also called anonymous users, cannot access any records by default. This affects all Salesforce orgs.
For more about the guest user implementation for Industries CPQ, see Guest User Enhancements Overview.
Beginning with CME Spring '20 Minor Release, Salesforce does not allow guest users to create and update records by default with the exception of Cart-Based and Digital Commerce APIs listed in this topic.