Like the message says, their server is not available at this time.
nostr:npub1gcxzte5zlkncx26j68ez60fzkvtkm9e0vrwdcvsjakxf9mu9qewqlfnj5z is there any reason why I cannot zap people using primal?
Discussion
The message already has dozens of zaps though and this is only happens with primal. Are you saying their node is not stable?
Yep. Probably all lightning servers get unstable from time to time. Sometimes they are just too busy to reply. In this case, the server replied with an HTTP status of 403 which means the server is live and understoord the request but refuses to authorize it.
lnd at scale needs witchcraft 😎