The reason they are letting us know they will fix after the new years is because
a. To avoid people complaining about silent nerfs like Enfys Nest (things they meant to go around fixing but took a month to fix)
b. They have limited time, manpower and with Christmas break (holidays) they can't get around to fixing the bug
c. The point of letting us know is to prevent people from wasting resources on zeta Finn
d. They need time to come up with a solution and the ramifications of that solution, and major decisions shouldn't be made on a drop of the hat but needs careful planning
Letting us know immediately ahead of time is GOOD communication. It would've been awful after 2 weeks of everyone using the P3 solo, CG just does a content update and changes Finn's zeta without prior notice