Recurrency "End On" date in datepicker is different with RecurrencyRule's one.
Steps to reproduce:
open series from the example, set Recurrency's End selector to date option, set date to Sep 9th.
Actual result: recurrency rule contains UNTIL=20200910T000000Z.
Save and open series again: recurrency's End date is now Sep 10th.
Changing it to Sep 9th and saving brings no changes.