Use jsonapi to post a flagging needs permission 'administer flaggings' and always failed to "A flagging can't be moved to another entity."

Created patch from the fork.

I've been using MR 15, but it's no longer applying to the newest dev version of the module. It looks like there are conflicts in src/Entity/Flagging.php and src/FlagService.php. Will report back if I'm able to get it taken care of myself.

As a work around, maybe you can implement hook_ENTITY_TYPE_access()</a> in a custom module:

/**
 * Implements hook_ENTITY_TYPE_access().
 */
function YOURMODULE_flagging_access(EntityInterface $entity, $operation, AccountInterface $account) {
  if ($entity->getFlagId() === 'your_flag_id' && $operation === 'view') {
      ... maybe some other logic ...
      return AccessResult::allowed();
  }
  return AccessResult::neutral();
}