Wikidata should support localised digits (e.g. the ones used in Farsi Wikipedia). Unlike many other languages, Persian does not use the Latin digits (1, 2, 3, ...) but its own digits (۱, ۲, ۳, ...)
The bug can be explained using an example: In https://www.wikidata.org/wiki/Q95963597?uselang=fa the date values for properties P571 and P585 are using the correct digits for the day of the month (such as "۱۷ مارس" for "17 March") but not for the year ("2020" should be shown as "۲۰۲۰" but isn't). Screenshot below.
The problem also appears when you try to edit the data:
