Mims suffered an ankle injury during a recent training camp practice and then suffered a calf injury during his rehab, a source confirmed to ESPN's Rich Cimini. He will become an unrestricted free agent.
Because the trade was conditional on Mims making the Lions' 53-man roster, Detroit will get back its 2025 sixth-round pick and a 2025 seventh-round pick will return to New York.
Before the injuries, Mims had been impressive in camp, but the Lions' receiving corps has taken a hit lately with Amon-Ra St. Brown suffering an ankle injury and Jameson Williams being sidelined for the remainder of the preseason with a hamstring injury.
Moore, 28, has caught six passes for 104 yards in 18 career games with the Chargers over three seasons.