If the todayBtn: 'linked' option is set but startDate/endDate doesn't allow selection of today's date, the button should either be disabled or fall back to todayBtn: true behaviour.
See on demo.
Even though the start date is set to "01-01-2060", the "today" button is still clickable and it still sets the value to the current date.
I also doesn't respect daysOfWeekDisabled.
I have the same issue. If the start Date is greater than today or end Date less than today then the today button should not be visible. The today button is still clickable in this case.