Got the confirmation for INC-224729 -- Pega Calendar Gadget deprecated (Raised in May 17, 2022 )
After checks we know that your current OOTB control which is deprecated and will be not supported.
For now you can use two other controls like :
PegaGadget-CalenderView ( Calendar view gadget) -> It contains all HTMLs elements, activities and section that are used for the calendar. Also, there is an OOTB activity - Show Calendar which you can use on your Pega App.
pxCalendar -> Second option to use Calendar, this section from @baseclass to show the calendar.