I would like to ask for your opinion whether such a takeoff is a violation of FCOM procedures
If by FCOM you mean Airbusī Flight Crew Operating Manual then I would say yes, most likely (I do not fly the product and have never read the manual) such a takeoff would violate Airbusī recommendations.
The airline may be bound by their own and different regulations that may permit such a departure (I boubt it). I am in no way advocating such an operation and I donīt care that it looked like most of it blew off the wing prior to flight.
I fly a Boeing, such a departure would clearly and without a shread of doubt, be in violation of multiple regulations and company policies. I would expect to be sacked/terminated/fired for such an operation by my employer, have my license revoked by the authorities and likely never work in the industry again.