Am I mistaken, or was SS withheld up to a maximum total earnings limit per year? I’m pretty sure that’s the case, and would tend to favor, not discriminate against the wealthy.
No, the problem is on the benefit calculation.
The payroll tax is flat, up to the limit each year.
But, the benefit calculation is NOT flat. Depending on where you are on the income scale, every additional dollar of additional income (actually, average indexed monthly income over your working lifetime) results in 90 cents, 32 cents, or 15 cents being added to your monthly benefit.
So, the higher your average income, the percentage replaced by your Social Security benefit is lower. SS has always been effectively "means-tested".
Search for "Primary Insurance Amount" or PIA to see the details. The Social Security administration has a webpage about it, but there are many others that explain it as well.
I've paid to the limit for the last 30 years. That's a maximum contribution. When I retire, I won't be working 55 to 70 hours a week. I will live off my 401k. The class warriors would insist on "means testing" what I can take back out from the maximum confiscation applied to my paycheck since I was about 30 years old. What comes out should be directly proportional to what went in. No more. No less. No redistribution of your wealth to those who didn't earn it, nor theft by you of other people's contributions.