They're pretty sure the primordial environment was a hydrothermal vent in an anoxic high phosphorus soda lake with methane, ammonia, and UV exposure. Nowadays those lakes don't have the methane and ammonia, so that environment isn't there anymore. https://www.science.org/content/article/unusual-soda-lakes-m...

The surfaces of clay particles in these lakes have been dubbed "the primordial sandwich".

The early protocells were 'alive', they were self-replicating, but they required nutrients and metabolic processes that only existed near mineral surfaces and would starve if they drifted away. They had to evolve new enzymes to become 'free-living'.

So it looks like the LUCA was one of these early protocells with an incomplete metabolism.