After some quick googling I can't find any groups that support that.
I did find a poll that shows 64% of Americans support creating some path for undocumented immigrants to get legal status. I'm not sure you could call 64% a far left position though.
They don't "support unlimited immigration", they reject the legitimacy of national borders and of immigration as a concept.
For example here's the DSA explaining their view that the national border and immigration statuses are capitalist and imperialist tools to divide the working class: https://www.dsausa.org/blog/fighting-the-security-state-at-t...
I'm still not sure that's representative of the far left. Like I said, the more right wing libertarian position is probably the same, though for different reasons.
That this is being memory-holed, much like the ill-conceived bilingual education initiatives of the 90s, is actually a good sign, as it's proof that we're winning.
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.