Do you have some idea what they meant by extreme left leaning issues? I'd like to hear your take.

Sure: importing migrants with no end in sight while shutting down any convo over what the limit should be; there is no limit and you're racist if you disagree.

And it's not a principled position on open borders nor open migration but instead part of a double standard. These same people probably cheer on the protests in Mexico City against white gringos in Condesa.

That's how I'd summarize the far left position. The far right one is probably that migrants are bad. And I suppose the middle position is that there's a problem when immigration rate outpaces cultural assimilation.