Change record status: 
Project: 
Introduced in branch: 
9.2.x
Introduced in version: 
9.2.0-alpha1
Description: 

Drupal\jsonapi\Access\RelationshipFieldAccess and associated _jsonapi_relationship_field_access route access check is deprecated and is removed in Drupal 10. There is no replacement. JSON:API's route access checks are internal and are not part of its public API.

Impacts: 
Module developers