The NAT is using ADS-C not ADS-B and if the Flightglobal description of the problem is correct then the issue probably doesn't affect that reporting.
It would be a problem for any ANSP using ADS-B as the sole means of surveillance in busy airspace but as others have said few do. It is an example of the sort of issue that makes some believe you need to support ADS-B with other techniques such as multilateration if you want ADS-B to achieve separation standards similar to those obtained with radar.