Even kiwi did it.
I have referred kiwi to my cousin and didn't get referral benefits. At that time, a successful onboard entitles free neon membership.
The funny part is one day to fix this referral bug some developer from kiwi chatted with me on whatsapp to know details like the mobile number to which I referred , timestamps etc. I even shared these SS of chat to CS for referral benefit, they flatly denied saying system hasn't recognized as valid referral.