Anarchism

Certainly, pretty much all of them dealt with the question of justifying authority. That doesn't mean ofc that one should simply accepts the answers given.

That is also why I brought those topics up, bc they are the difficult ones in both ideologies. (justification/corruption of power [Marxism] vs. industrial production/class divide [Anarchism])

Also different Marxist authors reach different conclusions, but a general justification for transitional authority of one class is common ofc. A defense of revolutionary authority that is more approachable from a anarchist/libertarian standpoint is Rosa Luxemburgs "Reform or Revolution", in which she also criticizes the lack of democracy in the USSR. Engels "On Authority" is often suggested, but I find it too short and not thorough enough. Antonio Gramsci is also often credited with a nuanced examination with authority

I can attempt a simple sketch of what I think is a common argument (that doesn't do actual reading any justice) to justify state authority:

Marxists base their analysis on materialism. In their view what shapes the social order first and foremost are the material conditions of society, for the sake of the argument say the distribution of wealth (criminally oversimplified to the point its wrong). Individuals on opposing ends of the distribution have irreconcilable material interests (example: employer wants to pay low wages, employee wants high wages) but they share these interests with others in the same end of the distribution, those form classes.

One class has more influence over society (the owning class) and they shape the ruling ideology justifying them (implicitly) as the ruling class. (An argument that material conditions more so than rational thought shape an ideology is that the philosophers of the so called "age of reason" deemed private ownership self-evident as well as racism as sexism). The state becomes the instrument of one class to rule the other.

Since class interests are oppositional the ruling class will never voluntarily accept the oppressed class as equal (The narrative of "Class collaboration" is actually associated with fascism), therefore "class struggle" is inevitable.

The only seen way out of this is a dissolution of contradictions that arise from a divide in material conditions, this necessitates both the development of the productive forces to a point where scarcity doesn't necessarily begets class contradictions and the disenfranchisement ("proletarization") of the bourgeoisie, in short a dissolution of classes per se. The vehicle to bring about these changes needs to facilitate a power inversion between the classes (i.e. for de-privatization). Since that doesn't happen voluntarily revolutionary authority is necessary and the state is chosen as the instrument, which then acts as a tool of the proletariat to assert themselves over the burgeoisie, hence the term "dictatorship of the proletariat" (dotP). A succeeding socialist state brings the classes closer together until class contradictions dissolve and the material common interests align. At that point the ideals of anarchist and communist align as well.

Re corruption I don't know too much. I know Rosa Luxemburg has written about it too in her elaboration on the Russian revolution, I haven't read it though. Ofc the Maoist "cultural revolution" was somewhat of a (failed) attempt to preemptively prevent corruption. Nowadays the communist party of China follows thought around "self-revolution" which is directed against corruption, but again: superficial knowledge.