You told us that the myObject is {...someObject} as const. Did you also define someObject to be as const?

const a = {
  a: 0,
  b: 1,
};

const b = {
  ...a
} as const;

type B = typeof b[keyof typeof b]; // number

const a = {
  a: 0,
  b: 1,
} as const;

const b = {
  ...a
} as const;

type B = typeof b[keyof typeof b]; // 0 | 1