I guess it's because there are so many Earth Green Lantern,
Hal's ring is forged by himself and connected to Cosmic Grail.
Jess had a ring with Omega Effect but later got a new ring?
John had a ring tattoo during Snyder's JL run, was it explained?
Simon had like Emerald Vision or something during Humphries run?
Yeah, I guess it's hard to keep track of everything.