A camp where people are sent because of their ethnic background and where a large part of inmates die is a concentration camp, absolutely. Especially if human experiments are done on the inmates and torture is common.

I would not want my conditions to improve through slavery and torture of others. There is a big difference between you and me regarding that.

used that to show that the good the USSR did was outweighed by the bad.

Nope. I used it to show that it is possible that the good the USSR did was outweighed by the bad. That the concept exists. The Nazis are a warning example of what we must never become. It is super scary that it is not allowed to talk about them. In this case nothing like Nazis actions was under conversation, but sometimes things do look almost 1:1 the same as Germany looked in 1920's when the foundations for Nazism were laid and early 1930's. It is not good that it is considered Nazi apologia, because if we can't say aloud when things are going that way again, we will eventually end up Nazis ourselves.

I used to live in Germany, and it scared me that people there don't see that their way will eventually lead to rise of fascism again, no matter how understandable the principles behind the "do not compare anything to Nazis" rule is! When it comes again, Germans are not going to anything to stop it, and will stop anyone who does try to. Except, of course, if it uses the swastika. Then it will be stopped.

But, now back to the actual subject!

The Workers in the Soviet Union were not sent to camps to die en mass.

Correct, it was largely based on the ethnic background, not so much on social strata. For example Latvians were sent there in such amounts that now almost 50 % of Latvians speak Russian as their main language. It also does not really matter if they were sent there en mass or not, when several millions from around Soviet Union were sent there and 70 % of them died. Camps where millions are sent and less than a third come back alive is not something that can ever be considered acceptable. Camps where you put six people to sleep in a space built for one or two are not okay. It is not okay, it was not okay, and it never will be okay. And it is not okay to defend them.

Then there are some claims that you just let hanging in the air:

No, Finland did not achieve better metrics at a larger scale

I already explained that Finland [was between 1917 and 1991] Imperialist

Finland extract[ed] superprofits off of exploitation of the Global South [between 1917 and 1991].

You need to elaborate on those. I did alter the quotes, because in the context of comparing countries' growth 1917–1991 whatever happened after 1991 is not really relevant. The altered parts are marked clearly.

“ruling class” -- would have sucked at their job given that they dramatically lowered wealth inequality.

The job of the ruling class is not to maximize wealth inequality. They very often do that, yes, but it is not their job. Lowering wealth inequality is a sign of the ruling class is doing their job correctly, not incorrectly. I do not understand why you would think otherwise.