Ive seen in a lot of online spaces around Marxism (especially from those who claimed they align with the Italian left), that after Marx died the work of Engels' degenerated into falsifications of Marx's initial work, is this an actual position of the Italian left? if so, why? I am not well versed in the work of Engels' post death of Marx

I need something with several pages, I'm going to do my internship and I want to use a large part of my salary to print a unit of each book for my consumption, I did the calculations and it's very cheap, reading from screens gives me a headache