Compare value inside of use-deep-compare-effect

Question

This is a part of use-deep-compare-effect source code

export function useDeepCompareMemoize<T>(value: T) {
  const ref = React.useRef<T>(value)
  const signalRef = React.useRef<number>(0)

  if (!deepEqual(value, ref.current)) {
    ref.current = value
    signalRef.current += 1
  }

  // eslint-disable-next-line react-hooks/exhaustive-deps
  return React.useMemo(() => ref.current, [signalRef.current])
}

In source code, compare the values like this.

export function useDeepCompareMemoize<T>(value: T) {
  const ref = React.useRef<T>(value)
  ...
}

  ...
  if (!deepEqual(value, ref.current)) {
  ...

deepEqual is a function that compares whether two parameters are deep equivalent.

I expect deepEqual(value, ref.current) to return always true. But it is not.

Why does this code work correctly?