Calendar all-day event tracking

I monitor all-day events in a google calendar.
The event vanishes from the calendar at midnight.
Take a two day event 19 Apr 2020 to 21 Apr 2020
This event is visible in the calendar until midnight on 20th Apr 2020. It then vanishes.
I have no control over the time recorded - it is always 00:00:00

  1. If there is a way round this ignore my next bit…!

  2. So, I want to know on 21st Apr 2020 that the event is ending but the calendar event is no longer there.
    Is there a way to set a sensor during the time it is visible that is not cleared down when the event vanishes. Ie I want to retain the end date after the event has completed - until the next event comes along and changes it.