I just want to known who invite the member in public channel.

I try: I make a public channel and I set a telegram bot admin in it.Then I create a invite link to the channel by telegram bot api and I send the link to someone.He click the invite link in telegram and jump to the channel.My telegram bot got a chat member update but there are no invite link info in this update.And the invite link in telegram app show no body invite by the link,yet.While I change the channel to private,the invite link will show who was invite by it and the invite link info will be existed with chat_member update.
I expect: I can get the invite link info in chat member update while the channel is public.