You've received the message because Netreg has encountered a mismatch between the security contact that claimed an IP address (individually or by subnet) and the security contact that registered a subdomain.
(Note: In Netreg the assignment of a subdomain enables the transfer of IP address responsibility to the right party, but does not assign security contact responsibility).
For example, if security contact A registers a subdomain xyz.berkeley.edu and another security contact B claims subnet a.b.c.0/24 and there is a set of hostnames defined in DNS:
security contact A and B will each get a message suggesting that the IP addresses be transferred from B to A.
Either security contact can initiate the transfer: Security contact A can 'request to take'; B can 'request to give'.
If the other party agrees and approves the transfer then B ends up with the subnet and A has 3 individual IP records out of that subnet because of its subdomain registration.
Remember: NetReg does not automatically make the transfer because there may be alternate solutions to resolve the discrepancy. In the above example, security contact A could relinquish the IP addresses, or have their DNS hostname changed to something not in the xyz subdomain.
You are receiving this "IP address to transfer" message so that you can choose the best solution.