Bug in the calendar widget (v8.0 release & master).
This bug was even captured on the documentation page and for some reason no one noticed. In the examples section: the screenshot displays the current date on Feb 24, 2021, and in the example source code, it is set to Feb 23.
I locate bug in function “static void highlight_update (lv_obj_t * obj)” (lv_calendar.c)
now: uint8_t day_first = get_day_of_week (calendar-> today.year, calendar-> today.month, calendar-> today.day - 1);
uint8_t day_first = get_day_of_week (calendar-> today.year, calendar-> today.month, 0);
The function should return the day of the week of the first day of the month, not for the current date.