              ]
          else:
              return []
  
      def _check_backend_specific_checks(self, **kwargs):
          app_label = self.model._meta.app_label
          for db in connections:
              if router.allow_migrate(db, app_label, model_name=self.model._meta.model_name):
                  return connections[db].validation.check_field(self, **kwargs)
          return []
 
</s> remove         for db in connections:
            if router.allow_migrate(db, app_label, model_name=self.model._meta.model_name):
                return connections[db].validation.check_field(self, **kwargs)
        return []
 </s> add         errors = []
        for alias in databases:
            if router.allow_migrate(alias, app_label, model_name=self.model._meta.model_name):
                errors.extend(connections[alias].validation.check_field(self, **kwargs))
        return errors </s> remove             self.assertEqual(field.check(), [error])
 </s> add             self.assertEqual(field.check(databases={'default'}), [error]) </s> remove         self.assertEqual(field.check(), [
 </s> add         self.assertEqual(field.check(databases=self.databases), [ </s> remove                 model.check()
 </s> add                 model.check(databases={'default', 'other'}) </s> remove                 model.check()
 </s> add                 model.check(databases={'default', 'other'})
    def _check_backend_specific_checks(self, databases=None, **kwargs):
        if databases is None:
            return []
              ]
          else:
              return []
  
    def _check_backend_specific_checks(self, databases=None, **kwargs):
        if databases is None:
            return []
          app_label = self.model._meta.app_label
          for db in connections:
              if router.allow_migrate(db, app_label, model_name=self.model._meta.model_name):
                  return connections[db].validation.check_field(self, **kwargs)
          return []
keep keep keep keep replace keep keep keep keep keep
 Fixed #31286 -- Made database specific fields checks databases aware.

Follow up to 0b83c8cc4db95812f1e15ca19d78614e94cf38dd. 
django/db/models/fields/__init__.py