Calendar left-hand pane "sticks" when choosing a later date

[antony]

See REPL:

https://svelte.dev/repl/ce9459e1e2dc45f9b0786487654e112e?version=3.35.0

Then select a date far in the future say, 22nd nov 2021, for both start and end

Note that re-opening the calendar shows the left hand pane as the original start date's month.

I would expect it to show the newly selected start date's month