Anti-N antibodies are not guaranteed to develop in everyone who recovers naturally from COVID-19.
While those lower Anti-N antibodies have been observed in those who’ve been infected and vaccinated, that doesn’t mean that your overall immunity is compromised. Those who’ve been vaccinated just have a different antibody, Anti-S, which is protein-based because the vaccine is protein based.
You’re arguing that because there are less Anti-N antibodies that overall immunity is lower. The reason why that doesn’t work is because Anti-N is only one type of immunity.
By your logic, if someone had Anti-N and Anti-S antibodies (infected who been vaccinated) they would have more immunity. However the data does not support that:
“Importantly, the anti-S and anti-N antibodies combined do not equal greater immunity against COVID-19,” Experts at Meedan Health Desk.
Further:
The mRNA vaccines have been found to be five times more effective at preventing hospitalizations than natural immunity. Which wouldn’t make sense if they were compromising our immune systems in any way.