A little bit of perspective on this.
I was a member of a PS Class A PRSI scheme from the 1980s - and many were members since the 1970s. Normal Retirement age was 60 but there was no Supplementary pension whatsoever. People didn't generally retire at 60 but if they did they either worked elsewhere or relied on whatever benefit they were eligible for from Social Welfare until pension age - unemployment. Or, of course, they relied on the Occ Pension.
The introduction of the Supplementary was a big step forward for us jubilation! I guess it only came about because all new public servants from 1996 started on a Class A basis and the unions pushed for some concession to ease the discrepancy with the old Class Ds. The introduction of the Supplementary in 1998 was a perk and never a part of the "the pension". A public sector perk. There were no deductions from wages for it. There were similar coordinated pensions in some firms in the private sector then and there was no Supplementary introduced for them.
So, yes, there was an anomaly between between Class As and Class Ds but this was always the case. A far bigger "anomaly" came for new entrants after 2004 when normal retirement age was raised to 65. They too could retire at 60 but with an actuarial reduction to 75% of occ. pension and no Supplementary. That transition was much bigger than was that from Class A to Class D in 1996. And then there was a bigger jump still with the Single Scheme pension from 2013. There were always going to be changes needed to make PS pensions more sustainable, given the huge increase in numbers over the past 60 years, and I don't think the 1996-2004 entrants were uniquely disadvantaged in this.
I would note that the " uniformed grades" with a compulsory retirement age of 60 were particularly hit by the Class A scheme. That really was an anomaly and there should have been some system in their pension scheme to take account of it.
Now let the projectiles fall!