Well, true. In the case of the great Chinese famine, and arguably the famine in Ukraine & Western Russia, this is a basically accurate description.

But what I'm saying is that this isn't a useful discussion because it can easily be spun different ways. For example someone might point out that a huge number of famine and malnution deaths have also occurred under capitalism, and they may even find a source saying it's higher per capita. It's an incredibly nebulous thing to quantify, but a suitably motivated person can make statistics say anything they want. Are the people dying now in Sudan being killed by 'capitalism' because they're caught in a tug-of-war between capitalist blocs? How many other deaths in all the pointless wars do we add to the total?

You can also easily get lost in the numbers of what deaths count as being caused by the ideology; people are currently dying in Cuba as a more-or-less direct result of Trump's fuel and trade blockade, but many would (quite disingenuously) argue that this is the fault of the Cuban government. If even a small number of deaths are included in the count which have a dubious claim to be caused by ideology, these can be seized upon to delegitimise the claim of all of them. The 100M figure including the deaths of Nazi soldiers on the eastern front is an example of this.

All of this distracts from why these people died. As you said, famines are not natural and are almost always caused by human activity, whether that's poor agricultural policy, social conflict, mismanagement of natural resources, poor trade policy, or deliberate starvation. Usually, this is combined with natural events such as drought, floods, earthquakes etc. which push things to breaking point.

Famines that occured in communist and capitalist systems had a range of causes, and blanketing political attempts to attribute them to leftwing or rightwing ideas are unhelpful and will not help prevent them from happening again. It's just a big unproductive pissing match with no conclusion and no respect for the people who died.