netherite helmed swapped in chest for gold

i pulled out a gold helmet from a chest in overworld. then swapped it with the netherite one on my head. then put netherite into chest. went into nether. came back to overworld. opened chest only to see the gold helmet there and no netherite helm. i looked on character and the gold one was equiped. so somehow the netherite got turned into the gold one. the gold ones are identical in condition and enchants. no netherite helm properties at all. netherite one is gone.