Whether you're new to the mission or a seasoned expert, The Planetary Society's Chang'e-4 homepage is your go-to resource guide.
Longjiang-2’s original orbit would have been stable over a very long period. Estévez states that the orbit periapsis was lowered by 500 kilometers on 24 January, “so that orbital perturbations would eventually force the satellite to collide with the Moon. This was done to put an end to the mission and to avoid leaving debris in orbit.” In a later post, he predicted that the impact would fall on the far side of the Moon, thus avoiding Apollo and Luna landing sites.
When it’s possible, it’s a responsible move to discard spacecraft while they’re still commandable, to prevent derelict ships from threatening the operations of functional ones. Kudos to Longjiang-2’s operators for keeping lunar orbit clean!