Some questions.. your quarantine tank is cycled, right? Could be ammonia, nitrite poisoning, or high nitrates poisoning and they had it and want to get out of the conditions in the tank. You have to find a way to seal up the top more. Tetras and all fish have the tendency to jump at times randomly and unfortunately, sometimes out of the tank; it's their nature. I sadly had cardinals jump out every once in a long while, so I could relate.. Also, the neons don't exactly freak out after the lights are off, they're just going to a instinctive, nocturnal state or something..
55 gallon Rainbowfish species/Harlequin rasboras community Dutch scape low-tech planted tank
60 gallon Bala shark low-tech planted tank
250 gallon Community Tiger Oscar/Red hook silver dollar/Silver dollars/BR Parrots/ PB Jack Dempsey/Clown loaches/Tinfoil barb/Roseline sharks/Barbs Monster fish tank