There are lots of kinds of “leftisms” with lots of different attitudes toward landlords—but to take Georgism as a concrete example that exclusively focuses on land ownership:

Georgists would say that the portion of the rent equal to the market rent of the unimproved lot—including the value generated by the presence of the surrounding community and infrastructure—should go back to the community, but the portion of the rent contributed by the presence of buildings and other improvements should go to the owner of the improvements.