If the government prevents you from evicting, doesn't that mean they have some ownership of the property ala eminent domain? If the government stops you from making decisions over your property isn't that a backdoor way to achieve eminent domain?
Maybe, but it is not a de jure taking. There are vast numbers of restrictions on what one can do with one's property and on businesses that one can conduct on that property. Zoning ordinances prevent me from setting up a chemical factory where I have my house; I can't build it up 4 stories and there is an obligatory setback from the property line for any extension. I can't freely build on my land, I need government permission in the form of a permit. This is allowed (Agins v. City of Tiburon, 447 U.S. 255), when the regulatory action advances a legitimate governmental goal and therefore the action is not a taking. The government might "take" land by rendering it useless without the formality of condemnation (United States v. Dickinson, 331 U.S. 745). But a moratorium on evictions does not render the property useless. The tenant remains liable for rent.