In https://docs.camunda.org/manual/7.16/reference/bpmn20/events/timer-events/, examples which contain Date such as R4/2016-03-11T12:13/PT5M should contain the timezone in the value. For example: specify the time in UTC (e.g., 2016-03-11T12:13:14Z) or with a UTC-relative offset (e.g., 2016-03-11T12:13:14+01).

Examples that need to be updated:
Link: https://docs.camunda.org/manual/7.16/reference/bpmn20/events/timer-events/#timer-start-event

• <startEvent id="theStart">
    <timerEventDefinition>
      <timeCycle>R4/2016-03-11T12:13/PT5M</timeCycle>
    </timerEventDefinition>
  </startEvent>
  

•  <startEvent id="theStart">
    <timerEventDefinition>
      <timeDate>2016-03-11T12:13:14</timeDate>
    </timerEventDefinition>
  </startEvent>