Of course there are plenty of left wing disinformation actors. It's fairly well accepted that the huge 'Bernie Bros' online movement was amplified in the same way the Trump movement was.

I don't blame the article for not including it because left wing disinformation has been mostly ineffective and uninteresting though.

The most interesting exceptions are the AntiVaxxer movement (sometimes left associated) and the Caexit groups, which is a story worth looking at.

Edit: it does include an example of left wing fake news: the false accusation of police burning a tent. It's actually pretty short on right wing examples (although I didn't read all the Chinese cases, so some of them maybe).