When you reset the atom it becomes an empty state saved in storage. According to the docs https://recoiljs.org/docs/guides/atom-effects/#asynchronous-storage-persistence the key should be removed when it's a default value (at least for now)

the fix is to simply add this to onSet

if (newValue instanceof DefaultValue) {
      if(state.hasOwnProperty(node.key)) delete state[node.key];
} else {
     state[node.key] = newValue
}