This is most certainly software rather than Aerodynamics, read the second page of the AD. Group 1 aircraft with L102 ELACs fitted the AFM TR has to be placed in the manual with 30 days. Group 2 aircraft without L102 ELACs fitted the AFM limitation is only applicable once the L102 is installed. This alone means it affects just one ELAC standard.
I’ve not seen the TR but if is below 100ft it will be something to do with the landing aspect of the flight control software. The A321neo from my understanding doesn’t have flare law compared to a CEO, its been replaced with something more akin to direct law where the sidestick input is proportional to output during that flight phase.