What passes for “social conservatism” is increasingly more any principled position which doesn’t align with the co-optation of identity politics by liberalism, to the extent that so many “radical leftists” to whom Stalin and Mao where too lenient make up their positions on worldwide matters by asking “What’s their policy on trans rights?”.

“Leftists” believe in all sorts of things, but most Marxist-Leninist parties I know in Europe would likely be classified as such. You mention “anti sex work”, which is sort of new to me since I was unaware that the hallmark of being a radical leftist today was the acceptance and defence of a system of sexual exploitation - might as well start using the “well they do it to buy expensive iPhones” line of thought that is so common in those that try to justify it. Radical feminism always saw the obvious nature of “sex work” (which is completely obvious to anyone travelling to the third-world but somehow in the first it is trendy to think of it as a “choice”), but I suppose those can easily be labelled “TERFs” and be done with.

The same applies to everything else you mentioned: the sort of topics that will make the delight of “democratic socialist” parties like the DSA or the many pseudo-radical European parties like SYRIZA/Podemos, they can be so very modern and “socially progressive” while playing their part in the campaign against communist parties.

The example of the KKE (with who I have several divergences) is a perfect example of this: SYRIZA, that great “LGBT friendly” party, the henchman of the EU and the IMF in Greece... but hey, they are “progressive” and the KKE “reactionary”.

We have the same issue where I am: voting against euthanasia is “regressive left”, being against the legalisation of prostitution is “reactionary”, having doubts about sex reassignment policies in infants is “outdated”.

I’m not going into the details of any of this topics and not even saying all parties have similar positions or that they are actually the right ones, but overall the way these topics are bundled together in a neat package is presently a result of ideology.