The required validation on radios was fixed in a more recent version. Upgrading Payload will help, but not completely fix your problem.
Radio inputs in the browser don't work the way you want. There is no way to deselect a value without adding a clear button. You need a third option for 'null' in your list it seems.
It can only be realized by select, but it is inconvenient
required and give that a shot.
@zhounewz also if your options only need to be true and false, you could use a checkbox field here.
@zhounewz what version of payload are you on?
@JessChowdhury "payload": "1.2.5"