Yes, it might sound worrisome, but I dont think you are pushing authoritarian ideology by using Lemmy. The code itself is fine. The code is not authoritarian. The server which hosts your account is also not authoritarian.

Lemmy is, right now, the best alternative for a reddit-like platform. It is something created for the users, by the users. By using lemmy, you are not enriching the wallets of the shareholders. By using something like reddit, you provide content and a select few get to buy a new yacht.

Also, plenty of people are contributing code to lemmy. It is no longer just these 2. The code is also Open-Source. Anyone can fork it and create a new version of lemmy, with compatibility with the current version of lemmy. By using lemmy, you are allowing the possibility that, at any time in the future, someone else comes and says "I have some ideas to improve lemmy, let's do this on my own terms", forks it and continues the work without massively spliting the community.

I don't think comparing communism with fasism, at least when it comes to exterminating ethnic minorities is accurate. this is an opinion shared by academics, including coauthors of "The Black Book of Communism" (the book which claims communism killed 80M-100M people, though the upper end of the range is the one which has more attention. this number is disputed, again also by coauthors)

I could explain why I believe you shouldn't do this in my own words, but I will use the words of Nicolas Werth, one of the three main coauthors who distanced themselves from the book:

Death camps did not exist in the Soviet Union.

and

The more you compare Communism and Nazism, the more the differences are obvious.

Another quote I will give is from Amir Weiner an American historian and associate professor of Soviet history at Stanford University who wrote:

[w]hen Stalin's successors opened the gates of the Gulag, they allowed 3 million inmates to return home. When the Allies liberated the Nazi death camps, they found thousands of human skeletons barely alive awaiting what they knew to be inevitable execution.

I sourced these quotes from Wikipedia: "The Black Book of Communism", references 19 and 14.

My point isn't to say the Soviet Union, or other states which had or have Marxist-Leninist governments are without critique, but that comparing them to the III Reich, at the very least diminishes the crimes committed by Nazis and makes analysis of the aforementioned States more muddy.

I think you mean 80 years. Unless there were genociding gas chambers in 1973 I haven't heard about.

(And I would have been put in one too, just not in 1973.)